South of the northern wall of Durostorum Drustur is the place where in 352 Dorostol martyr – St. Emilian was burned and in the second half of the 9th century was established the remarkable temple. Perhaps this is the cathedral church of the first Drustur bishop after the baptism of Bishop Nikolay. It is assumed that this is one of the seven episcopal cathedrals established by Prince St. Boris-Mihail after the 870. It is a church with three naves with apses, narthex with a total length of 25.40 meters and a width of 14,70 m. After the 927, when Drustur became the residence of the first Bulgarian patriarch Damian, the church was converted into a basilica with a sintron cross with three stages, pulpit and a patriarchal room in the north nave.
In the 11th and 12th century is the cathedral church of the Byzantine bishops and metropolis of Drustur. At that time the bishop was buried in front of the altar’s gates. After the Tartars’ invasion in 1242 it has been restored and continues to serve as a cathedral for the Bulgarian bishops until the 14th century. Then, near the northern facade was built the bell tower.
To the west of the church lays the patriarchal residence from the 10th century, and in the east is the patriarchal bath. Drustur Patriarchate is the first national Patriarchate in the Christian world after Apostolic Patriarchate in Rome, Alexandria, Antioch, Jerusalem and Constantinople.