Saints Sergius church and Bacchus (Abu Serga) the oldest church in Cairo and Christian churches. It is dedicated to two early martyrs and traditionally believed to have been built on the spot where the Holy Family, Joseph, Mary and the infant Christ, rested at the end of their trip to Egypt They may have lived here while Joseph worked at the fortress.
Hence, the church is of significant historical importance, and in fact, it is where many patriarchs of the Coptic Church were elected. The first to be elected here was Patriarch Isaac (681-692) it is the Episcopal church of Cairo, and it was the Episcopal See of Misr old Cairo that replaced the former See of Babylon. Many bishops of the See were consecrated in the Church until the reign of Patriarch Christodoulou (1047-1077). The church is dedicated to Sergius and Bacchus, who were soldier-saints that were martyred during the 4th century in Syria by the Roman Emperor, Maximilan.
The building was probably constructed during the 5th century. It was burned during the fire of Fustat during the reign of Marwan II around 750. It was then restored during the 8th century, and has been rebuilt and restored constantly since medieval times.
However it is still considered to be a model of the early Coptic churches and its basilican style is easily recognizable. This church resembles religious structures in Constantinople and Rome. It has two aisles with a western return aisle (a passage at the west end of the church), along with a tripartite sanctuary that measures 17 x 27 meters and is 15 meters high. Within the sanctuary is an altar surmounted by a wooden canopy supported by four pillars. On the east wall of the sanctuary raises a fine, semi-circular tribune with seven steps. There was probably a khurus, a transverse room preceding the sanctuary, in front of the sanctuary but which no longer exists.