Scientists speculate that this is a precipitation of caves. But when you see them from above, you believe that this is something... extraterestrial!

The absolute silence that prevails within them "breaks" only by bird tweets that sound with resonance because of the circular craters.

In one of two craters there are two churches of Byzantine and post-Byzantine period (11th-14th century). The depth of the small crater is 80 meters and its diameter is 150 meters.

Internal vertical walls where someone could descend through a tiered portico are rooted the small churches of Transfiguration (toward the north) and St. George's (towards the south).

Both churches are carved into the rock.

Inside the St. George's church there are inscriptions in Latin characters: A historical inscription that marks the passage of Thomas Palaeologus, the ruler of the Peloponnese as well as an old stone baptistery.

East of the church there is a small tank, whose walls are covered with a kind of porcelain, and east to a height of 25 meters in a hole called "Askitareio" where hermits reached with rope.

In the Twin Craters during the spring season takes place the celebration of tulips as Gemini area is one of the few areas in Greece where one can come across native tulips.