South of the north wall, after the adoption  of Christianity, in the second half of IX c. an imposing temple was erected. As an architectural plan it was a three-nave basilica with a narthex and three apses. Probably is was the cathedral church of the first Bishop of Drastar - Bishop Nikolay. After 927  it was rebuilt and became the residence of the first Bulgarian Patriarch Damian.

In  XI - XII c. the church was a cathedral of Byzantine bishops. After the Tatar invasion in 1242 it was rebuilt and continued to function until the end of XIV c. as a temple to Bulgarian metropolitans.

To the west of the basilica  a patriarchal residence  was built dating from the X c. . Around the inner courtyard there were chained premises where the patriarchs and bishops were probably housed. There was a bath  to the east of the cathedral  that was a part of the complex.