This is one of the largest byzantine monuments in Greece, of the composite octagonal type. Its construction is associated with the establishment of the Archdiocese of Christianoupolis by Alexios I Komnenos in the late 11th century. Its interior was decorated with high quality marble architectural sculpture, marble revetments, mosaic floors and wall paintings, reflecting the affluence of its donors and making a direct association with the emperor’s family very tempting. Attached to the west of the church is a complex building with a complicated construction history, identified by most scholars as a bishop’s residence. The dome and a large section of the upper part of the church collapsed after the devastating earthquake that hit Filiatra in 1886. Since then the monument was in ruins for several decades.