Nesebur, the ancient Mesembria, was founded in 510 BC by Greek Chalcedonians on an earlier Thracian settlement site. Mesembria prospered as a trade center until the Roman conquest in the first century. Under the Byzantine Empire, Mesembria regained its former importance and its prosperity during that time is evidenced by a number of imposing churches built in the 5th and 6th centuries. Byzantine nobles continued to build churches until the town contained as many as forty. Although Nesebur passed back and forth between Byzantium and Bulgaria many times beginning in the 9th century, the town miraculously remained physically unscathed throughout. Its strategic importance diminished however and Nesebur ceased as a trading center in the 18th century. Today its residents are fishermen or are involved in tourism. Declared a World Heritage Site by UNESCO, this picturesque island town boasts the most varied architecture in the Balkans. See Hellenistic, Roman, Byzantine, Turkish and Bulgarian architecture pleasantly juxtaposed along labyrinthine lanes teeming with activity, charming cafes and small boutiques.