Athens’ bizarre underground phenomenon

Just 40km north of Athens lies a vast cave where visitors have reported water dripping upwards, ghostly voices, electronics going out of control, glowing orbs and more.

Dimitrios Makridopoulos has always been fascinated by the preternatural. Devouring books about occult phenomena from childhood to adulthood, he soon became curious about the pyramid-shaped mountain of Penteli, located about 15km north-west of Athens. “[I was] drawn to the energy of this mysterious and ancient mountain,” he told me.

Penteli is globally acclaimed for its ancient quarries and the incomparably crystalline structure and golden-hued tint of its marble that was used to construct the sacred temple of Parthenon as well as other glorious monuments. Yet, it was Davelis Cave, located on the mountain’s south-west side, that particularly piqued Makridopoulos’ interest.

Resting in and above an ancient marble quarry and averaging a width of 45m and a height of 62m, Davelis Cave is a vast, mesmerising and steeply descending grotto that could well serve as the backdrop to a horror movie. Visitors have reported electronics going out of control, glowing orbs, ineffable creatures, water dripping upwards, ghostly voices, spooky etchings, remnants of satanic rituals and more.

You may also be interested in:

• A beer made from Irish cave walls

• South America’s other ‘Easter Island’

• The deadliest place in Earth’s history?

In 2015, Makridopoulos packed up a ‘spirit box’ (a device said to enable communication with spirits through the use of radio frequency) and an infrared camera, and headed for Penteli with some friends. It was January and the mountain was shrouded in fog. This made it virtually impossible for him and the others to make out what lay even 5m ahead, but Penteli compensated with gifts at every turn, from chunks of precious marble from its plentiful ancient quarries to pieces of iron bearing evidence (according to Makridopoulos) of cryptic military experiments conducted in the cave in the late 1970s and ‘80s.

“From the minute I stepped into this unspoilt and pure place, I became one with it. I was surrounded by an inexplicable, otherworldly energy... I felt eyes following my every move... I could not see or hear anything with my five senses, but I knew,” Makridopoulos said.

The 29-year-old computer technician remembers his surprise when his electrical appliances confirmed back at home what he’d felt in the cave. His spirit box captured what sounded like a choir of angelic children’s voices chanting in ancient Greek. “It was the language of the pixies,” he said. He is also adamant his infrared camera recorded ghostly apparitions near the cave’s centre, and a tiny, pitch-black creature lurking at the entrance of the hollow. “There, can you see it?” Makridopoulos asked with intense interest when showing me the photos a few days before my own journey to the cave.

Davelis Cave was used as a shrine as far back as the 5th Century, when devotees worshipped Pan, their goat-footed god of shepherds and orgies. During the Middle Ages, hermits and Orthodox monks started flocking to Penteli either for spiritual retreats or because they were religiously persecuted, and the place was named ‘Σπήλαιο των Αμώμων’ (‘Cave of the Immaculate’), hence the presence of two adjacent Byzantine chapels built directly into the cave’s entrance.

In the 19th Century, notorious brigand Christos Natsios, aka Davelis, allegedly squatted in the cave with his gang. There’s even a legend that the brigand, who had a fling with the French duchess Placentia, discovered tunnels zigzagging through the cave’s guts and terminating at his lover’s mansion in the village of Pendeli in Athens’ northern suburbs. Whatever the truth, the allure of past-era cabals of desperados was catalytic in renaming the spine-chilling catacomb in honour of the iconic outlaw.

On a mellow January 2019 morning, I visited Davelis Cave with a couple of friends. After driving through a maze of Penteli’s slopes, we left the car at the beginning of a dirt road. Walking up the unmarked trail and regularly hopping over small puddles of slush and muddy water, the panoramic views of Athens stretching out to the Saronic Gulf made up for what at times seemed like a fruitless hike.

Finally, after about 25 minutes, the GPS insisted we turn left. There, at the foot of a rugged, ochre-grey cliff was a crescent-shaped opening in the rock. To the right of it sat the adjoined chapels of St Spyridon and St Nicholas. On the left was a concrete structure, built by the Greek military as an outpost and now seemingly abandoned. Cautiously walking towards the cave, I felt an intense pull inside, where I could see fragmented rocks scattered across the cave floor and cascades of stalactites streaming down in front of moss-riddled walls. There was hollow sound of water dripping from the roof. Though claustrophobic and fearful of what awaited me, I wanted to head deeper inside. But once in the cavern itself, I realised couldn’t go much further as the tunnels leading from the cave had been blocked up.

“These were the tunnels the Nato and the Greek military concreted to cover their tracks,” Makridopoulos later told me.

On 6 October 1977, Greek magazine Tahidromos published an article saying that the Greek military had begun strictly confidential operations inside Davelis Cave. The place was classified as military and sealed off to the public. Some talked about the establishment of a rocket base overseen by Nato, a rumour further fuelled by a US military base in neighbouring Nea Makri district. In 1982, Giorgos Balanos, a well-known Greek author of paranormal and science fiction, wrote of apocryphal underground tunnels, nuclear weapons and mind-control projects in his The Enigma of Penteli book, stirring up even more suspicion about what was going on in the underground chamber. In the 1990s, the Greek government attempted to re-initiate their projects in Davelis Cave; this time, newspaper front pages screamed about nuclear experiments. Soon, all the indeterminate works in the cave came to a halt, and future visitors would be met with a few new tunnels stopping at dead-end cave walls while the old ones were closed off.

Despite the tunnels being inaccessible, conspiracy theories still abound, such as Makridopoulos telling me that Nato extracted the marble of Penteli to create advanced satellites during the Cold War space race.

Whatever the truth, a 2002 study by Georgios D Papadeas of the Institute of Geology and Mineral Exploration of Greece agrees that there is something special about the cave. Scientists have found slate enriched with graphite between the layers of the Pentelic marble, which makes the mountain a good conductor of electromagnetic waves.

Additionally, the Pentelic marble itself possesses certain scientific properties that lead it to give electric charge under high-pressure conditions (which, for Makridopoulos and others, might explain some of the bizarre electromagnetic phenomena observed there, such as the dizziness and disorientation some visitors feel). That said, Dimitrios Papanikolaou, emeritus professor at the Department of Dynamic, Tectonic and Applied Geology at the University of Athens, who has been studying Penteli since 1973, chalks any obsession with paranormal phenomena inside Davelis Cave to “idiosyncratic forces at work”.

“Penteli has a one-of-a-kind rock composition resulting from millions of years of metamorphosis. But that’s just about it,” he told me from his office at the University of Athens campus the day before I visited the cave, and describing all Davelis Cave-related paranormal sightings and hearings as “vagaries” and “placebo effects”.

“The summit of Penteli was an air force base. Athens is a Nato city,” he continued. “Penteli overlooks the Aegean Sea, so everything that happened in the cave and nearby in the ‘70s and ‘80s happened with the intent of armouring the Attica Basin.” As for the blocked-off tunnels? “They were dangerous, they had to do it,” the professor replied. “But what we don’t understand, we ascribe to myth.”

Notwithstanding, what Papanikolaou himself admits is that certain places are distinguished by an unexampled magnetism. “When Athens was at its peak, people devoted all their intellect to extracting the best marble in the world. Maybe some places have a distinct energy of their own: the energy of thousands of human beings that once lived and thrived there, but that’s just about it.”

‘Magnetised’ is just a fraction of what Makridopoulos claims to feel in the proximity of Davelis Cave. He is already spearheading a team called ‘Orfeas Group’, which has a popular blog dedicated to exploring supernatural phenomena.

Even I felt a gravitational pull towards the cave the day I visited. As I stood at the entrance, a beam of light passed through the cave’s mouth and lit up the place, almost as if to guide me forward. The words of the professor about the energy certain places have amassed over time rang true more than ever.

Join more than three million BBC Travel fans by liking us on Facebook, or follow us on Twitter and Instagram.

If you liked this story, sign up for the weekly bbc.com features newsletter called "If You Only Read 6 Things This Week". A handpicked selection of stories from BBC Future, Culture, Capital and Travel, delivered to your inbox every Friday.

{"image":{"pid":""}}