Nessebar is a town in Burgas Province, on Bulgaria’s Black Sea coast. The cobbled streets of the old town, which sits on a promontory, are lined with ruins such as Byzantine-era fortifications and baths. The ruins of the 5th-century Church of St. Sofia include stone columns and large arched windows. The 11th-century Church of St. Stephen houses hundreds of mural paintings and a huge, richly decorated altarpiece.