In terms of architecture, it is the most important Byzantine church of Messenia. It comprises two adjoined buildings, the church and a structure to the west. The church is of the composite, octagonal domed type, distinguished by the careful "cloisonne" masonry, decorated with large stone crosses on the lower sections of the walls. The facades are plain, with very poor brick and sculpture ornaments. Few fragments of wall paintings, dated to the 12th century, are preserved inside the church.
During the Medieval period, the church was the Cathedral of the metropolitan bishopric of Christianoupolis, which was established at the end of the 11th century. The building attached to the west of the church was used as an episcopal palace and possibly as a defensive tower in the Late Byzantine period. The monument is dated to the 11th or, most likely, to the 12th century A.D.
Near the site of Christianoi, the following monuments are worth visiting:
- the traditional settlement of Kyparissia with the important castle called "Arcadia", built during the Byzantine period,
- the small churches of Analepsis (13th century), St. George Bourianon (17th century) and Panaghia Vlacherna (first half of the 19th century) at Philiatra.