Some of its bishops are mentioned in synods in Serdica and other nearby towns. From this period are the ensembles of the Small and Great (Large, Big) basilica. The Grave (Funeral) basilica with a necropolis is located east of the theatre...
    A small Basilica was discovered in excavations made before the World War II between 1936-1938. At first it was thought to be an ancient palace, but in the later research from 1960–1964, it became clear that it was an early Christian basilica. There is a decorated floor mosaic made by the technique "opus sectile" within the basilica and several rooms have been unearthed. The first room was used for baptizing and the second room in has a floor mosaic made by the technique "opus tessellatum". After creation of the complex Great Basilica, the function of these rooms was changed. By discovering the walls, architectonic plastic and floors were reconstructed electronically.
     The Great Basilica is a monumental building with a room of open porch colonnades, a room of egzonarteks, one of narteks, two north annexes, and a room of three south annexes. The floors of these rooms are mosaic with geometric and floral designs. The mosaic in the narthex is of early Byzantine art, a big composition at a size of 100 m (328 ft). There are birds, trees, bushes, a red dog, which is a symbol of paradise, and animals beasts as a domain of the earth. This mosaic dates from the end of the 6th century. The Great Basilica is built on top of another one and was made sometime between the 4th to 6th century.