It is an underground corridor of about 20km in length, on the eastern side of Nea Fokea , which has been curved on the natural rock and ends in a rectangular underground  chamber. It is probably an ancient burial construction that, during the Byzantine period was turned into a church again. Tradition says that Apostle Paul was teaching at Ierissos at the time when haunted, and with his life in danger, he went into a hole in the earth. Then passing through an underground corridor, he arrived at Kassandra and came out at the chamber of the "agiasma".