At the foot of Mount Didymos in Argolida there is a unique geological phenomenon that causes awe to the visitor. Two huge craters created probably by landslides due to the groundwater of the mountain. The craters are about the same diameter, so the locals called them twin caves or dolines. The two craters are circular in shape and are visible from a great distance due to their size. From above, in particular, they are an incredible, eerie, alien spectacle. One is located at the foot of the mountain and is called large cave and the other is in the valley and is called small cave. The depth of the small crater is 80 meters and its diameter is 150 meters. The first is visible even from far, but the second one is even more impressive. Visitors can get into it through a small cavernous entrance.
Into this crater two churches can be found, the church of Agios Georgios and the church of Metamorphosis easily to be visited and eyed up. Both churches are carved into the rock and belong to the Byzantine and post-Byzantine period (11th - 14th century). Inside St. George there are inscriptions in Latin characters, a historic inscription that marks the passage of Thomas Paleologos, Ruler of the Peloponnese as well as an old stone baptistery.