In Nesebar, a small town on the Black Sea which is on the UNESCO World Heritage List, is the empty shell of a basilica which once was an astonishing building. St Sophia, now known as the Old Bishopric, was built in the 5th Century, supposedly over the agora of the ancient Mesambria and a temple of Apollo.
Under the Romans, Nesebar preserved its status as a coveted centre of commerce
As the city's cathedral, it was 25.5 m long and decorated with mosaics. There were seats for the bishop's council in the apse. The church's greatest treasure were the holy relics of St Theodorus, but in 1257 they were stolen by Venetians and taken to the Serenissima during the sack of Mesambria. By the end of the 18th Century the church was abandoned, and religious life concentrated in the number of later, mediaeval churches which fill the town's narrow streets.