The Great Cave, one of the oldest monasteries in Greece and it is located 10 km northwest of Kalavrita, built in vertical 12 meter cliff. At the top of the rock there is an old tower, while in front of the monastery lies the gorge of Vouraikos. The monastery, which according to tradition was built the second half of the 4th century AD and several times burned ( 840 AD, 1400, 1943 by the Germans). In the early times served as a hermitage, during the Venetian domination as the residence of the Bishop of Patras while during the national revolution of 1821 was used as a supply center for the Greek fighters. In 1827, 300 monks lived there. The monastery houses the icon of Our Lady and the Child, which according to tradition, was found in 362 AD by two monks from Thessaloniki, Theodore and Simon, in a cave at Chelmos mountain. This image, made by Luke the Evangelist, was discovered by the monks being guided by a shepherdess named Euphrosyne. The source of the cave is known as the "daughter’s source". The church preserves frescoes dated 1653, marble floors of the 14th century and a wooden temple. In the restored sacristy relics of priceless religious and historical significance are exposed. The silver casing of Panagia Spileotissa and more. In the library are held Greek, Venetian and Turkish documents from the 17th century.