Davelis Cave (Greek: Σπήλαιο Νταβέλη) is a well-known cave in Penteli, a mountain to the north of Athens, Greece. Davelis Cave was brought to light ca. the 5th century BC. The surrounding area was used as a marble quarry by the builders of the Acropolis, and the cave was discovered by chance, during works for the extraction of marble.
Name: The cave's name comes from the wide belief that an infamous 19th century brigand called Davelis (real name Christos Natsios) used the cave as a hideout. The story says that Davelis hid his treasure inside the cave.
The official name of the cave is simply "Cave of Pendeli".
Antiquity: In Antiquity, the cave was a place of worship for the followers of Pan and the nymphs. There is a much smaller cave a few hundred meters up the mountain called Nymphaion or Nymph shrine.
During the Middle Ages, it was used by Orthodox Christian hermits, and later a small church was built at the entrance of the cave, featuring an unusual double layout: one part devoted to Saint Spyridon and one to Saint Nicholas. This unusual layout has led to the construction of the church being associated with Gnostics.
The cave is also believed to have been (and possibly still is) used by other religious groups, mainly occultists.
Source: wikipedia.org