The rotunda, also called Golden or Simeon’s church shows the highest achievements of the proto- Bulgarian’s monumental art. The object’s research started in 1927 and continued several years until its complete discovery. Simeon’s cousin’s Tudor Doksov’s note says that the church was built in the first years of the tenth century. The church is situated  about 200 m. on the south of the southern port of the Inner town. Builders made an artificial embankment over which the church was built. The Golden church has central plan. The round nave (the central room) has a diameter of 10,50 m. and is divided by twelve semicircular niches in three of which the entrances are on the western wall and the twelfth one on the east has formed the altar apse. There were twelve white marble columns before the front sides of the niches 0,60 m. away from them which used to support the circular gallery and a line of columns for bearing the roof. There are remains of a pulpit (a lifted platform where the priest preaches) in the middle of the central room (the nave). A rectangular narthex was built next to the nave in which four symmetrically located columns used to support the upper floor from which people passed in the nave’s gallery. There are two cylindrical towers in the narthex’s two corners; there are remains of a winding stairs leading to the second floor in the northern part. The narthex has two rooms from north and south with two outer rooms and almost square atrium (a yard) on the west. There was a marble baptistery on the eastern wall of the round room. The atrium’s walls as well as the ones of the nave were separated by niches in front of which there was a colonnade. There is a well in the center of the yard for mass purposes.

Three inscription were inscribed on the narthex’s southern wall during the church’ s construction. One of them says in Cyrillic alphabet that the church’s construction was under the guidance of Chartophylax Pavel (an ecclesiastical officer in charge of official documents). The other two are inscribed in Glagolitic alphabet. A few funerals were performed around the church and inside.

The Rotunda is not only unique with its original architecture and plan structure but also because of its rich decoration combining marble carving, painted ceramics and glass mosaics. There are Hellenistic samples, birds’ images and hunting scenes in the sculpture decoration.

A monastery complex was found on the south of the Rotunda made later than the church. The chain building found a few meters on the south of the church is directed west- east and related to the monks’ residential needs. The scriptoriums (a room used for copying manuscripts) and workshops for painted ceramics found, one of which on the east under the Rotunda itself, were centers not only of religious and educational and literary life but also one of the places for making the Preslav white clay ceramics.