The 4th century basilica of Saint Sophia Church at Serdica (Sofia, Bulgaria) was rebuilt in the 5th century and ultimately replaced by a new monumental basilica in the late 6th century, and some construction phases continued into the 8th century. This basilica was the cathedral of Serdica and was one of three basilicas known to lie outside the walls; three more churches were within the walled city, of which the Church of Saint George was a former Roman bath built in the 4th century, and another was a former Mithraeum. The basilicas were associated with cemeteries with Christian inscriptions and burials.