The church of St. Jason and St. Sosipater, who were disciples of St Paul and brought Christianity to Corfu, is the most important monument of the Middle Byzantine period on the island. It is one of the earliestexamples of the two-columned type church, i.e. a rectangular structure with a dome over the center of the cross that is inscribed within the plan of the building.
The lower part of the structure is built of large blocks of poros from the nearby ruins of the ancient city of Kerkyra. The typically Byzantine cloisonné masonry was used higher up, consisting of dressed stones with bricks in between. The interior of the church was once entirely frescoed; now wall paintings survive at various points, dating to the 11th-14th centuries. The marble columns are from older buildings and the Baroque chancel screen is an 18th century intervention. The sarcophagi on either side of the door in the chancel screen are attributed to the church’s patrons, St Jason and St Sosipater. The belfry and the structure on the north-west corner of the church date to the 17th century.
According to written sources, the church was themain church (katholikon) of a monastery already in the 15th century. Katherine, wife of Thomas Palaiologos (brother of the last Byzantine emperor, Constantine XI), sought refuge here when Constantinople fell to the Ottomans in 1453. Throughout the Postbyzantine period, the monastery was linked with noted scholars ans artists, owned a considerable estate, and even today preserves some important icons and treasures.