In the ruins of the Sostis Monastery on Mount Papikion
North of the settlement of Sostis there are ruins of a large monastery complex dating to the 11th-14th century. The katholikon, the major church building of the monastery, belongs to the type of three-aisled basilica where the aisles are defined by double colonnades. The floor of the main church was made of marble while the narthex was made of bricks. The marble members found throughout the temple belonged to the iconostasis, the wall separating the nave from the sanctuary in the church. In the room next to the temple utensils and everyday objects were found, such as cups, plates, knives, which undoubtedly testify that it is the refectory, the monastic dining hall of the monastery. Other outbuildings that have been excavated are the monks' cells and the water tank.
Mount Papikion was an important monastic center during the Byzantine period. From the end of the 11th century there are written sources, mainly of Byzantine historians, that are confirmed by the archeological research, for the existence of temples and monasteries in the area. Unfortunately after the 12th century the monastic center declined and was gradually abandoned. From the decoration of the monastic complexes it is certain that there was an artistic influence from the nearby important centers of the Byzantine Empire but also from Constantinople. In most of them, the buildings of the complexes are partially preserved in a dilapidated condition. The access to the area is from the settlements of Sostis and Polyanthos via forest roads.