The Mountain

Fifteen kilometers northeast of Athens, a mountain of white marble rises above the sprawl of the Attica basin. The Greeks called it Pentelikon. Today it is simply Penteli. Its highest point, the peak Pyrgari, reaches 1,109 meters. On a clear day, you can see it from the Acropolis, from Marathon, from the coast at Elefsina. The mountain is covered in pine forest across sixty or seventy percent of its surface, and the suburbs of Athens—Vrilissia, Ekali, Dionysos, Gerakas—crowd against its lower slopes.

But the mountain’s fame has nothing to do with its height or its forests. Mount Penteli is famous for what lies beneath its skin.

Pentelic Marble

Pentelic marble is white with a uniform, faint yellow tint that gives it a golden hue under sunlight.¹ It is calcitic in composition, fine-grained, with quartz as an accessory mineral. It has been quarried since at least the sixth century BC, and it was used to build the most important structures of classical Athens: the Parthenon, the Propylaea, the Temple of Athena Nike, the Erechtheion.²

Later, Pentelic marble was exported to Rome, where it appeared in buildings and sculptures across the imperial capital. The quarries on Mount Penteli operated continuously—with interruptions for wars, invasions, and periods of decline—from the sixth century BC until the 1940s. Today the ancient quarry is protected by law and used exclusively to obtain replacement material for the ongoing Acropolis Restoration Project.

The marble is not merely decorative. It is structurally exceptional. The Parthenon contains an estimated 22,000 tons of it, cut with such precision that the joints between blocks are nearly invisible even today, two and a half millennia after construction.

The Marble Road

How do you move 22,000 tons of marble from a quarry at 700 meters elevation down to a building site in the city below?

You build a road.

The ancient transport route from the Penteli quarries to the Acropolis is still partly preserved. It is known informally as the Marble Road, and it has been researched and fully documented by Professor Manolis Korres, the chief Acropolis restoration architect, in his book From Pentelicon to the Parthenon (1995).³

The road follows the natural contour of the land, maintaining a continuous downhill grade from quarry to city. The quarried blocks—some weighing many tons—were loaded onto wooden sledges and dragged down the slope. The surface of the road still preserves the ruts worn by the sledges and the holes where wooden supports and braking posts were anchored into the rock. Walking this road today, you are walking the same path that the marble of the Parthenon traveled twenty-five centuries ago.

The Spilia Quarry

At approximately 700 meters elevation on the southwestern slope of Mount Penteli, the ancient quarry called Spilia opens into the mountainside. The rock faces here are sheer vertical cliffs, cut with tools whose marks remain visible on the marble surface. Scattered about the quarry floor are abandoned blocks and column drums—pieces that were started but never finished, or finished but never transported. Edward Dodwell, an English traveler who visited the site on June 22, 1805, described the scene:

The quarry is grand, and is cut into perpendicular precipices; the marks of the tools are still visible upon its surface. Several frusta of columns and large masses have been left scattered about.⁴

At the base of these perpendicular cliffs, where the quarry meets the living rock of the mountain, there is a cave.

The Cave

Davelis Cave—or, more formally, the Cave of Penteli—is a large natural cavern opening at the base of the Spilia quarry cliff. Its mouth is a crescent-shaped opening roughly 45 meters wide, framed by the vertical marble walls of the quarry above and on either side. The cave extends approximately 112 meters into the mountain. At its deepest, the ceiling rises to more than 20 meters.

The coordinates are 38° 04’ 15” N, 23° 52’ 37” E. The elevation is approximately 700 meters above sea level.⁵

Inside the Main Chamber

The floor of the cave is uneven, sloping upward toward the rear. Stalactites and stalagmites have formed in places, though many were damaged or destroyed during military construction in the late twentieth century. The walls bear the marks of both natural geological processes and human activity across many centuries: chisel marks from ancient quarrying, niches cut for votive offerings, graffiti from Byzantine monks, and—more recently—the raw concrete and rebar of military engineering.

Light penetrates the main chamber from the wide entrance. As you move deeper, the natural light fades and the temperature drops. Near the back of the main chamber, the cave divides into a network of narrower passages and tunnels that extend further into the mountain. At least one of these tunnels leads to a small underground pond.

Dodwell, continuing his description from 1805:

At the base of the precipice we find some natural caverns, which have been improved by art: one of the caverns contains the ruins of a church, in which the singular mixture of broken arches and subterraneous passages, cut through the marble rock, receiving from without a dim and mysterious light, has a peculiarly striking and picturesque effect; which a mass of pendant ivy, nearly closing the entrance of the cavern, contributes to augment.⁶

The Tunnel Network

Behind the main chamber, a series of passages extend deeper into Mount Penteli. The full extent of this tunnel network is not known. Some passages are natural fissures in the marble, widened by water over geological time. Others may have been enlarged by human activity—quarrying, hermit habitation, or military construction.

The seventeenth-century Turkish traveler Evliya Çelebi claimed that a monk of Penteli showed him extensive underground galleries, and it is probable that their entrance was gained through this cave.⁷

Many of the rear tunnels are no longer accessible. During the military construction of 1977–1983, natural passages were destroyed or blocked with tons of rubble and concrete. The accessible portions of the tunnel network today are limited compared to what existed before the military intervention.

The Cave’s Many Names

The cave has been known by several names across its long history:

• The Spilia Quarry Cave — its functional designation, referring to its location within the ancient quarry.

• The Cave of the Amomon (Spilaio Amomon) — from the Greek amomon, meaning “blameless” or “sinless,” referring to the ascetic monks who inhabited the mountain’s many caves beginning around the eighth century AD. The entire mountain was called the “Mountain of the Amomon” during this period.⁸

• The Cave of Penteli (Spilia Penteles) — the official modern name, used by the Greek Ministry of Culture.⁹

• Davelis Cave (Spilia Ntaveli) — the popular name, acquired in the nineteenth century from its association with the brigand Christos Davelis.

Visitors Across the Centuries

The quarry and cave have attracted visitors since at least the eighteenth century. Among the earliest documented visitors were the English travelers Richard Chandler, who described the quarry in his Travels in Greece (1776),¹⁰ and Edward Dodwell, whose 1805 description is quoted above.

In the twentieth century, the husband-and-wife speleologist team of Giannis and Anna Petrochilos conducted a thorough documentation of the cave’s structure. In 1982, Greek author Giorgos Balanos published The Enigma of Penteli, a popular book describing apocryphal underground tunnels, nuclear weapons, and mind-control projects, which significantly amplified public interest in the cave.¹¹

Today the cave is accessible to the public, though it lies off marked trails and requires some effort to reach. There is no public transportation beyond the village of Neo Penteli on the lower slopes. There are no gates, guards, or visitor facilities.

The God of the Wild

A popular claim, repeated in virtually every tourist guide and online article about Davelis Cave, is that the cave was an ancient shrine to Pan, the goat-footed god of shepherds, wilderness, and rustic music. Artifacts depicting Pan and the Nymphs have been found. Niches cut into the walls once held statues and offerings. A hollow in the wall bears a small water pool of unknown purpose.

There is only one problem with this story: it appears to be about the wrong cave.

Two Caves, One Mountain

According to Travlos (1988) and Goette (2001), there is no evidence of ancient religious activity at the Davelis Cave itself.¹² The shrine of Pan and the Nymphs was located in a much smaller cave further up the slope to the northeast, at an elevation of approximately 800 meters—about 100 meters higher than Davelis Cave.

This smaller cave, the Nymphaion, was discovered and partially excavated in 1952 and re-examined in 1975. Among the finds were lamps, terracotta figurines of Pan and the Nymphs, and two votive marble reliefs, now in the National Archaeological Museum in Athens.¹³ The shrine appears to have been active from the fifth century BC through the Roman period.

The conflation of the two caves—the large Davelis Cave below and the small Nymphaion above—is ubiquitous in popular accounts. Nearly every article, blog post, and YouTube video about Davelis Cave claims that Pan was worshiped there. This is, at best, imprecise. The Pan shrine was nearby, on the same mountain, but it was a different cave entirely.

Pan on Penteli

That said, the worship of Pan on Mount Penteli is well attested and deserves attention in its own right.

Pan was the god of shepherds and flocks, of mountain wilds and rustic music. He was depicted with the horns, legs, and hindquarters of a goat, and his worship was closely associated with caves, grottoes, and wild places. The most famous Cave of Pan in Attica was at Eleusis, but shrines to Pan existed in caves across the Greek world.

The Penteli Nymphaion was a classic example of such a cave shrine. The terracotta figurines found there depict Pan playing his syrinx (pan-pipes) alongside dancing nymphs. The votive reliefs show similar scenes. The lamps indicate that worship took place deep enough inside the cave to require artificial light.

Mount Penteli, with its forests, shepherds, and remote caves, was natural Pan territory. The mountain was home to the Daou Penteli Monastery and to scattered pastoral communities that tended flocks on its slopes for centuries. Pan’s presence here is entirely unsurprising.

What Happened to the Nymphaion

The smaller cave that housed the Pan shrine has been “greatly destroyed by quarrying operations during recent decades,” according to Athens123.com.¹⁴ The military construction of the 1970s and 1980s, which focused on the larger Davelis Cave below, may also have affected the Nymphaion site higher up the slope, though this is not documented in detail.

The artifacts from the Nymphaion—the figurines, reliefs, and lamps—survive in the National Archaeological Museum. They are the only physical evidence of ancient religious practice on this part of Mount Penteli.

The Sinless Ones

Around the eighth century AD, something changed on Mount Penteli. Monks began to arrive.

The Mountain of Amomon

Orthodox Christian hermits, seeking solitude and spiritual retreat, were drawn to the mountain’s many caves and hollows. Some came voluntarily, choosing the ascetic life. Others came out of necessity, fleeing religious persecution during periods of iconoclasm or political upheaval.¹⁵

Mount Penteli, with more than sixty known caves, offered abundant shelter. The hermits carved crosses, angels, and eagles into the rock walls of the caves they inhabited. These rock-cut graffiti, found in Davelis Cave and elsewhere on the mountain, have been provisionally dated to the Late Roman or Early Byzantine period—roughly the seventh to eighth centuries AD—on the basis of their style.¹⁶

The mountain itself acquired a new name during this period: the Mountain of the Amomon (Amomon)—the Sinless Ones, or the Blameless. The name honored the monks who had made the mountain their home.

The Word Amomon

The Greek word amomon is a compound of the alpha-privative a- (without) and momos (blame, blemish, reproach). It means “without blame,” “without blemish,” “sinless.” In classical Greek, momos was also the name of the god of mockery and fault-finding.

The word appears in the New Testament. In Ephesians 1:4, Paul writes that God “chose us in him before the foundation of the world, that we should be holy and amomous before him” (RSV: “blameless”). The same word describes the ideal of the monk—without spot or blame before God.

When the monks named their mountain, they were not describing a prerequisite for entry. They were describing themselves, or rather, their aspiration: to live without sin, in caves of bare rock, on a mountain of white marble, closer to God.

The Carved Crosses

The inscriptions and carvings left by the monks in Davelis Cave include crosses of various styles, figures of angels with outspread wings, and stylized eagles—a common Byzantine motif. These are standard forms of Byzantine Christian devotional art, found in caves, churches, and rock-cut monasteries across the eastern Mediterranean.

They are not, as some popular accounts suggest, “spiritual wards” designed to seal away a supernatural threat. They are prayers in stone, left by men who lived in darkness and sought the light.

The Chapels

At the entrance to Davelis Cave, built directly into the rock at the threshold between daylight and darkness, stands a small double church. It is one of the most unusual ecclesiastical structures in Attica.

The Double Church

The church was constructed in two phases between the tenth and twelfth centuries.¹⁷ It consists of two adjoining chapels:

• The South Chapel (Saint Spyridon): The older of the two. This chapel was cut directly back into the rock wall of the cave itself, so that its rear wall is the living marble of Mount Penteli. Saint Spyridon of Trimythous was a fourth-century bishop of Cyprus, venerated as a wonderworker.

• The North Chapel (Saint Nicholas): Added later. This chapel was built of masonry with a small dome. The dome is inscribed with the date 1234. Saint Nicholas, the fourth-century Bishop of Myra, is one of the most widely venerated saints in Eastern Orthodoxy.

The unusual double layout—two separate chapels joined at the hip, each with its own dedication—has prompted some speculation that the church was constructed by Gnostics or another heterodox Christian group. There is no scholarly evidence for this. Double churches with separate dedications exist elsewhere in the Byzantine world and do not require a heterodox explanation.¹⁸

A simple sketch plan of the church was published by Soteriou in 1927, and a more detailed plan appears in Mouriki’s 1973–1974 study.

The Frescoes

The frescoes in the church date to the first half of the thirteenth century. They are similar in style and iconography to the wall paintings of the church of Saint Peter in Kalyvia Thorikou, in southeastern Attica.¹⁹

Among the subjects depicted was Michael Akominatos (also known as Michael Choniates), the last Greek Orthodox archbishop of Athens before the Latin conquest of 1204. Akominatos was a scholar and churchman who lamented the decline of Athens from its classical glory. His presence in the frescoes connects the cave chapel to a specific historical moment: the final years of Byzantine Athens before it fell to the Crusaders.

The frescoes survived in the cave for nearly eight centuries, protected by the constant temperature and darkness of the rock environment. They did not survive the twentieth century intact.

Damage and Preservation

During the military construction of the late 1970s and early 1980s, the church was damaged. When the military excavated the cave floor immediately behind the chapels, it became necessary to buttress the chapel foundations with concrete to prevent their collapse.²⁰

Some of the frescoes—including, presumably, the image of Archbishop Akominatos—were removed from the chapel walls and transferred to the Byzantine and Christian Museum in Athens for preservation.²¹ Whether this removal was carried out by the military or by cultural preservation authorities acting to save the frescoes from further military damage is not entirely clear from available sources.

In August 2024, forest fires on Mount Penteli caused additional minor damage to the chapels. The Greek Ministry of Culture confirmed significant damage to post-Byzantine churches in the area.²²

The Brigand

The cave bears the name of a man who may never have set foot in it.

Christos Natsios

Christos Natsios was born around 1832, probably in the town of Steiri in Boeotia, though some accounts place his origin in the nearby town of Arachova or in Styra on the island of Euboea.²³

For a time, Natsios worked as a shepherd, tending the flocks of the Daou Penteli Monastery in the Attic countryside and selling their milk in Athens. Another account says he tended the flocks of the Petraki Monastery, then located just outside Athens in what is now the Kolonaki district.

The story of how he became an outlaw involves a sequence of misfortunes that reads like a folk ballad—which, in Greece, it eventually became. The abbot of his monastery gave him a letter to deliver to a nun. Natsios, curious, had someone read it for him. Learning its contents, he began visiting the nun himself. The furious abbot reported him to the authorities for theft. Natsios was arrested, convicted, and punished by bastinado—the judicial beating of the soles of the feet, a common punishment in the Ottoman-influenced Greek legal system of the period.

After his release, he fled to the island of Euboea, fell in love with a priest’s daughter, was falsely identified as a military deserter, killed a soldier in a scuffle, and took to the mountains as an outlaw.

The Brigand Davelis

In the mountains, Natsios joined the gang of his mother’s cousin, a bandit named Kakarapis. He eventually formed his own gang, adopted the nickname Davelis—of uncertain etymology—and began robbing travelers, peasants, and shepherds across Attica and Boeotia, which was standard practice for brigand gangs in Greece at the time.²⁴

Davelis’s most famous exploit occurred in 1855, during the Crimean War. Athens was blockaded by British and French fleets, and the port of Piraeus was occupied by foreign troops to prevent Greece from joining the war on Russia’s side. Davelis descended on the city and kidnapped a French officer named Berteau (or Breteau) on the main road connecting Piraeus to Athens. The Greek government paid 30,000 gold drachmas in ransom for the officer’s release—an astronomical sum, paid as quickly as possible to avoid further foreign entanglement and to cover up the existing connections between brigands and politicians.

The End of Davelis

Davelis’s criminal career reached its peak in the spring of 1856, when he ambushed gendarmes in the town of Menidi in Attica, forcing them to surrender their weapons. The humiliated Gendarmerie launched a massive manhunt.

Around the same time, the written correspondence between Davelis and an Italian noblewoman, the Duchess Luisa Bacoli, was intercepted. Bacoli had been arranging safe passage for Davelis and his gang to Italy. With their escape route compromised, the brigands were tracked to the Zemeno pass on the foothills of Mount Parnassus.

In the ensuing battle on July 12, 1856, Davelis challenged his former lieutenant, Yiannis Megas—who had defected to the Gendarmerie—to single combat. Davelis shot Megas dead but was himself fatally stabbed by another gendarme. Folk tradition records his last words as: “Neither shall Davelis be in the mountains, nor shall Megas be in the palace.”

His head was cut off, brought to Athens, and displayed on a pike in Syntagma Square for several days as a warning to other bandits.²⁵

Did Davelis Use the Cave?

The association of Davelis with the cave on Mount Penteli is “not verifiable historically,” according to some sources.²⁶ The legend says he used it as a hideout and hid treasure deep inside. The legend also says there was a secret underground tunnel connecting the cave to a noblewoman’s mansion further down the slope.

Whether or not Davelis actually used the cave, his name stuck. By the late nineteenth century, the Cave of the Amomon had become Davelis Cave, and so it remains.

The Duchess

The legend of the tunnel connects Davelis Cave not to the Italian duchess Luisa Bacoli—Davelis’s actual documented romantic interest—but to a far more prominent and colorful figure: Sophie de Marbois-Lebrun, the Duchess of Plaisance.

Sophie de Marbois-Lebrun

Sophie de Marbois-Lebrun (1785–1854) was a Franco-American noblewoman of extraordinary wealth and eccentricity.²⁷ Her father was the Marquis de Marbois, a French diplomat who had served in Philadelphia. In 1802, she married Anne-Charles Lebrun, eldest son of Charles-François Lebrun—who, alongside Napoleon Bonaparte, had served as one of France’s three Consuls from 1799 to 1804.

The marriage was unhappy. Sophie separated from her husband without divorce and devoted herself to the cause of Greek independence. She and her daughter Eliza moved to Greece in 1830, settling first in Nafplion, then the capital. When Athens became the new capital in 1834, the Duchess followed.

She purchased large tracts of agricultural land, chiefly around Mount Penteli. She commissioned the Greek architect Stamatios Kleanthis to design a palace on the slopes of the mountain: Rododafni Castle, a neo-Gothic structure on what is now Lord Byron Street in Penteli—a relatively short distance from Davelis Cave.

Tragedy struck in 1836 when her daughter Eliza died of pneumonia in Beirut. The Duchess had the body embalmed and returned to Athens, where it was placed in a crypt beneath her temporary home. She later commissioned Kleanthis to build Rododafni Castle as both a residence and a final resting place for Eliza’s remains.

The Duchess was an iconoclast. She rejected Greek Orthodoxy and converted to Judaism, sponsoring the reconstruction of a synagogue in Halkida in 1849. She hosted salons on religion and politics, dispensed funds and titles to those she favored, and was a central figure in the social life of early Athens.

She died in 1854. Her nephew sold her lands to the Greek state. She is buried with her daughter in her Tower near Penteli.²⁸

The Tunnel Legend

The legend claims that Davelis had an affair with the Duchess and visited her nightly via a secret underground tunnel running from the cave to Rododafni Castle. Some versions of the legend extend the tunnel all the way to the Pentelikon Monastery.

The tunnel may have some basis in physical reality. Athens123.com reports that approximately 200 meters of tunnel was shown on Greek television by journalists, at which point the passage had collapsed, blocking further exploration.²⁹ Whether this tunnel is ancient, natural, or of more recent construction is unknown.

The Chronological Problem

The romantic legend has a fatal flaw. Wikipedia’s article on Christos Davelis states plainly:

These claims are most likely false, since all available evidence points to Davelis being active around mount Penteli only after the Duchess had died.³⁰

The Duchess of Plaisance died in 1854. Davelis was killed in 1856. His documented brigand career around Mount Penteli postdates the Duchess’s death. His actual romantic interest, as documented in intercepted correspondence, was the Italian duchess Luisa Bacoli—not Sophie de Plaisance.

The tunnel legend, the affair, the midnight visits through underground passages: it is almost certainly fiction. But it is persistent fiction. The legend has been repeated for over a century and a half, and it is the reason the cave bears a brigand’s name rather than the name of the sinless monks who lived there.

The Concrete

In 1977, something unprecedented happened at Davelis Cave. The Greek military arrived.

The Construction Begins

Workers and technicians cordoned off the cave with barbed wire. Armed guards were posted. Heavy machinery—bulldozers, drills, explosives—was brought up the mountain. The public was excluded. No explanation was given.

On October 6, 1977, Greek magazine Tachydromos published an article revealing that the Greek military had begun strictly confidential operations inside the cave. The site had been classified as a military zone under the authority of the Greek Ministry of National Defense.³¹

The exposure did not stop the work. It continued for six more years.

A Critical Timeline Note

Many popular accounts—including the YouTube video that prompted this book’s research—claim that the military arrived during the Greek military dictatorship (the “Regime of the Colonels”), which ruled Greece from April 21, 1967 to July 24, 1974.³²

This is incorrect. The documented construction at Davelis Cave began in 1977, three years after the junta fell and democracy was restored. The works were managed by the Ministry of National Defense of the democratic Greek government, not by a military dictatorship.

It is possible that there was some earlier military interest in the cave during the junta period, but no source documents large-scale construction before 1977.

What Was Built

The military works at Davelis Cave, as documented by Athens123.com with photographs and GPS coordinates, included:³³

• A concrete structure built into the cliff face to the left of the cave entrance, secured by a steel door. It is rumored that this structure contains (or blocks) the entrance to the natural underground tunnels.

• Tunnel #1: Accessed from a dirt track branching off the path to the cave. An artificial tunnel bored into the marble, heading toward the cave. It ends in a dead-end where work was halted—a rough marble face.

• Tunnel #2: Further along the track, below the cave. Another artificial tunnel, also heading toward the cave, also ending in a dead-end.

• A possible third tunnel, now buried under earth and rubble. Old photographs show an opening that has since been covered.

• Concrete buttresses inside the cave to support the Byzantine chapels, whose foundations were undermined when the military excavated the cave floor behind them.

• Various bore-holes and steep pipes emerging from the rock near the cave entrance.

The natural tunnels at the rear of the cave—the passages that had led to underground chambers and a small pond—were destroyed or blocked with tons of rubble during this period.

The Theories

With no official explanation forthcoming, rumors multiplied. The cave was:

• A secret NATO missile base

• A nuclear weapons storage facility

• A nuclear fallout shelter for the Greek government

• A US intelligence telecommunications hub

• A radar or communications base

The radar/communications theory is considered the most plausible by some observers.³⁴ Other military installations—both Greek and American—do exist on other parts of Mount Penteli. The mountain’s elevation and line-of-sight to the Attica basin would make it a logical location for such a facility.

But no theory has been confirmed. The Greek government has never issued an official statement about the purpose of the works.

1983: The Abandonment

In 1983, the construction stopped.

According to Athens123.com, “the intervention of the Ministry of Culture forced them to stop.”³⁵ Other sources describe the cessation in more dramatic terms: a sudden abandonment, equipment left on the ground, bags of cement hardening in the damp air, scaffolding hanging in the dark, concrete poured but never finished.

Whatever the cause, the result is visible today. The artificial tunnels end in rough-cut rock faces where boring machines stopped mid-stroke. Rebar protrudes from unfinished concrete walls. Tools, materials, and—according to one account—even a cache of cancer treatment drugs were left behind.³⁶

1990: The Failed Restart

In August 1990, the military attempted to resume work. Crews returned to the cave and large-scale operations began again.

This time, the media reacted immediately. Newspapers ran front-page stories. There was massive public outcry. The Greek Ministry of Culture intervened, and the works were shut down permanently.³⁷

No further military activity has occurred at the cave since 1990. The site remains as the military left it: a strange hybrid of ancient marble, Byzantine masonry, and Cold War concrete, open to anyone willing to make the hike.

The Darkness

After the military left, the cave did not become quiet. It became stranger.

The Paranormal Reports

Since at least the nineteenth century, visitors to the cave and its environs have reported phenomena that resist easy explanation. The reports include:³⁸

• Electronic devices—cameras, flashlights, phones—malfunction or shut down completely inside the cave.

• Water appears to flow upward on the cave walls rather than dripping downward.

• Visitors hear ghostly voices, chanting, or music with no identifiable source.

• Glowing orbs of light have been seen floating on a cloud of mist inside the cave.

• Shadowy, human-like figures made of mist appear and disappear.

• Footprints have been found pressed into fresh cement, leading to a wall and simply stopping, with no return tracks.

• Temperature fluctuations of up to 10°C have been recorded nightly at precisely 1:00 AM, accompanied by unexplained rooster-like calls, according to the Athens Society for Paranormal Research.

• Symbols and a mysterious handprint on the cave walls have allegedly changed location over time.

• Several people who entered the tunnel network have reportedly never emerged.

It is important to note that none of these claims have been verified by controlled scientific investigation. They exist in the realm of anecdote and personal testimony.

The Occultists

After the military departed, the cave became a magnet for occultist groups. Visitors have found puddles of melted black wax, spray-painted symbols, and animal carcasses at the site.³⁹ The cave’s reputation as a place of dark power, combined with its isolation and the absence of any official oversight, made it an attractive location for ritual activity.

The most notorious criminal case associated with occultism in this part of Attica involved the so-called “Satanists of Pallini,” a group of three young people—Assimakis Katsoulas, Manos Dimitrokalis, and Dimitra Margeti—who murdered two women in satanic rituals in 1992 and 1993. Their crimes occurred not at the cave itself but in the Koropi and Sesi areas of East Attica, and they were arrested at the end of 1993.⁴⁰ Katsoulas received two life sentences plus twelve years. The case shocked Greek society and cemented the association between the Penteli area and occult activity in the public imagination.

Whether any connection exists between the Satanists of Pallini and the ritual activity documented at Davelis Cave is unclear.

The Electromagnetic Hypothesis

Scientists and skeptics have proposed that many of the reported phenomena at Davelis Cave could have a geological explanation.

Mount Penteli is primarily marble with quartz as an accessory mineral. Quartz is piezoelectric: it can generate an electrical charge when subjected to mechanical stress. A mountain of marble under tectonic pressure could, in theory, produce localized electromagnetic anomalies.

A 2002 study examined electromagnetic disturbances in the broader Penteli area, and the results were published in the journal Natural Hazards and Earth System Sciences.⁴¹

More broadly, neuroscientist Michael Persinger of Laurentian University demonstrated through his “God Helmet” experiments that pulsed electromagnetic fields applied to the temporal lobes can induce subjective feelings of an invisible presence, religious awe, and hallucination-like experiences.⁴² If Davelis Cave does exhibit unusual electromagnetic properties—a possibility that remains unproven but is plausible given the geology—this could provide a naturalistic explanation for at least some of the subjective experiences reported by visitors.

The electromagnetic hypothesis does not, however, explain the abandoned military construction, the sealed tunnels, or the absence of any official explanation for the works.

The 2015 Investigation

In 2015, a paranormal investigator named Dimitrios Makridopoulos led a small team into the cave equipped with infrared cameras and a device he called a “spirit box”—an instrument that rapidly cycles through radio frequencies, producing bursts of white noise in which some investigators claim to hear disembodied voices.⁴³

According to Makridopoulos, his team experienced immediate disorientation upon entering the cave. The spirit box allegedly captured sounds resembling children chanting in an ancient Greek dialect. The infrared camera recorded what appeared to be a small, hovering form near the entrance to the central tunnel system.

Makridopoulos released his audio and video recordings to the media. The recordings have been met with skepticism by mainstream investigators, who note that spirit boxes, by their nature, produce random audio fragments that the human brain is prone to interpret as meaningful patterns—a well-documented phenomenon known as auditory pareidolia.

The Threshold

Davelis Cave sits at a threshold. It always has.

Geographically, it is the threshold between the city of Athens and the wilderness of Mount Penteli. Architecturally, the Byzantine chapels mark the threshold between daylight and darkness, between the open air and the tunnels that burrow into the heart of the mountain. Historically, it stands at the threshold between the documented and the undocumented, between what we know and what we do not.

What We Know

The facts of Davelis Cave are remarkable enough without embellishment:

• The marble of the Parthenon was quarried from this site 2,500 years ago. The tracks of the sledges that carried it are still visible on the Marble Road.

• A double Byzantine church with thirteenth-century frescoes was built into the cave’s mouth, and stood there for eight centuries before twentieth-century military construction damaged it.

• A nineteenth-century brigand whose head ended up on a pike in Syntagma Square gave the cave the name it still carries—even though he may never have used it.

• A Franco-American duchess who converted to Judaism, embalmed her daughter, and built a neo-Gothic castle on the slopes of the mountain became the subject of a romantic legend involving underground tunnels—even though she died before the brigand was active in the area.

• The Greek military spent six years (1977–1983) conducting secret construction inside the cave, damaging a Byzantine church in the process, and then abruptly abandoned the project, leaving equipment, materials, and unfinished concrete behind. They tried to restart in 1990 and were immediately shut down by public outcry.

• No official explanation for the military works has ever been given.

These are documented facts, supported by academic publications, government records, photographic evidence, and multiple independent journalistic accounts.

What We Do Not Know

The gaps in the record are equally striking:

• What was the military building? The most plausible theories—a communications base, a radar installation—are reasonable but unconfirmed. No documents have been released. No officials have spoken on the record.

• Why did the work stop in 1983? The Ministry of Culture’s intervention is documented, but the underlying cause—whether the project was abandoned for budgetary, political, or other reasons—is not.

• What lies behind the sealed tunnels? The natural passages at the rear of the cave were blocked with rubble and concrete. Their original extent, and what they contained, is unknown.

• Is there a genuine electromagnetic anomaly at the site? The piezoelectric properties of quartz-bearing marble under tectonic stress provide a theoretical mechanism, and the 2002 study found anomalies in the broader area, but no controlled measurement has been conducted inside the cave itself.

The Lure of the Unsolved

Davelis Cave endures in the imagination because it presents a genuine mystery wrapped in layers of legend. Each layer—Pan, the monks, the brigand, the Duchess, the military, the paranormal—adds another veil. The temptation, for any storyteller, is to weave these layers into a single coherent narrative: a supernatural force that the ancients worshiped, the monks feared, the brigand stumbled upon, and the military tried and failed to contain.

It is a compelling story. It is also, as far as the evidence shows, fiction.

The ancients worshiped Pan in a different cave. The monks were not performing exorcisms; they were praying. The brigand’s connection to the cave may be entirely legendary. The Duchess died before the brigand arrived. The military came three years after the junta, not during it. And no one has produced verifiable evidence that anything supernatural has ever occurred at the site.

What remains, stripped of legend, is a cave of extraordinary historical depth—a place where the marble of the Parthenon was born, where Byzantine monks carved crosses into living rock, where a romantic legend attached itself to a brigand and a noblewoman, and where, for reasons that remain unexplained, the Greek military spent six years pouring concrete into a mountain and then walked away.

That is mystery enough.

The Cave Today

As of 2026, Davelis Cave is open and accessible to anyone willing to make the hike from Neo Penteli. There are no gates, no guards, no signs, and no visitor facilities. The Byzantine chapels stand at the entrance, damaged but still standing. The military concrete is slowly decaying. The sealed tunnels remain sealed.

In August 2024, forest fires swept across Mount Penteli, causing additional minor damage to the chapels and the surrounding landscape. The Greek Ministry of Culture has acknowledged the damage but has not announced restoration plans.⁴⁴

The cave waits. It has been waiting for a very long time.

A Note on Sources

Every factual claim in this book is sourced. The principal academic references are:

• J. Travlos, Bildlexikon zur Topographie des antiken Attika (Tübingen: Wasmuth, 1988), pp. 329–331.

• H. Goette, Athens, Attica, and the Megarid: An Archaeological Guide (London: Routledge, 2001), pp. 259–262.

• G.A. Soteriou, “He spileia tes Penteles,” Hemerologion tes Megales Hellados 6 (1927), pp. 45–59.

• D. Mouriki, “Oi byzantines toichographies ton parekklision tes Spilias tes Penteles,” Deltion tes Christianikes Archaiologikes Etaireias 7 (1973–1974), pp. 79–119.

• M. Korres, From Pentelicon to the Parthenon (Athens: Melissa, 1995).

• P. Zoridis, “He spilia ton Nymphon tes Penteles,” Archaiologike Ephemeris 1977, Chronika, pp. 4–11.

For the historical context of brigandage in Greece, J.S. Koliopoulos, Brigands with a Cause (Oxford: Clarendon Press, 1987) is the standard reference.

The most detailed photographic documentation of the cave and its military constructions is maintained at Athens123.com.

The BBC Travel article “Athens’ bizarre underground phenomenon” by Stav Dimitropoulos (February 28, 2019) provides a balanced journalistic overview and was an important source for verifying the timeline of events.

Where claims could not be verified through academic or journalistic sources, this has been noted in the text.