Saint George Rotunda Church built
330 CE.
Shown on the map at 42.697°, 23.323°.
The Church of Saint George (Bulgarian: Ротонда „Свети Георги“, romanized: Rotonda "Sveti Georgi") is a late antique red brick rotunda in Sofia, Bulgaria. Built in the early 4th century CE as Roman baths, it became a church inside the walls of Serdica, capital of ancient Dacia Mediterranea during the Roman and Byzantine eras. The early Christian church is considered the oldest building in modern Sofia and belongs to the Bulgarian Orthodox Church. The building, a cylindrical domed structure built on a square base, is famous for the 12th-, 13th-, and 14th-century frescoes inside the central dome. Three layers of frescoes have been discovered, the earliest dating from the 10th century. Frescoes of 22 prophets over two metres (six point six feet) tall crown the dome. Painted over during the Ottoman era, when the building was used as a mosque, these frescoes were only uncovered and restored in the 20th century.
Text from the Wikipedia article Church of Saint George, Sofia, licensed CC BY-SA 4.0.