The Rotunda is located in the center of Sofia. It was built in the 4th century AD when Sofia was under the name of Serdica. It was then destroyed by the Huns, rebuilt and turned into a mosque by the Ottomans.

     Restoration work has revealed three layers of medieval frescoes, which had been hidden by plaster since the 16th century. Its frescoes were made by amateurs. According to historians and archeologists, those frescoes date to the middle of the 10th century and portray 22 prophets. The impressive cupola bears a fourteenth-century portrait of Christ, surrounded by four angels. To the east lie excavated foundations of the Roman settlement of Serdica. Nowadays the church is a museum.