Originally a Thracian settlement known as Menebria founded in the 2nd millennium BC, the town became a Greek colony when settled by Dorians from Megara at the beginning of the 6th century BC, and was an important trading centre from then on and a rival of Apollonia (Sozopol). Remains from the Hellenistic period include the acropolis, a temple of Apollo, and an agora. A wall which formed part of the Greek fortifications can still be seen on the north side of the peninsula. Bronze and silver coins were minted in the city since the 5th century BC and gold coins since the 3rd century BC.
The town fell under Roman rule in 71 BC, yet continued to enjoy privileges such as the right to mint its own coinage. It was one of the most important strongholds of the Byzantine Empire from the 5th century AD onwards, and was fought over by Byzantines and Bulgarians, being captured in 812 by Khan Krum after a two week siege only to be ceded back to Byzantium by Knyaz Boris I in 864 and reconquered by his son Tsar Simeon the Great. During the time of the Second Bulgarian Empire it was also contested by Bulgarian and Byzantine forces and enjoyed particular prosperity under Bulgarian tsar Ivan Alexander (1331-1371) until it was conquered by Crusaders led by Amadeus VI, Count of Savoy in 1366 and handed back to Byzantium. The Slavic version of the name, Nesebar or Mesebar, has been attested since the 11th century.
Monuments from the Middle Ages include the 5-6th century Stara Mitropoliya ("old bishopric"; also St Sophia), a basilica without a transept; the 10th century church of the Virgin; and the 11th century Nova Mitropoliya ("new bishopric"; also St Stephen) which continued to be embellished until the 18th century. In the 13th and 14th century a remarkable series of churches were built: St Theodore, St Paraskeva, St Michael and St Gabriel, and St John Aliturgetos.The capture of the town by the Turks from the Byzantine Empire in 1453 marked the start of its decline, but its architectural heritage remained and was enriched in the 19th century by the construction of wooden houses in the Eastern Rumelian style typical for the Bulgarian Black Sea Coast during this period. After the Liberation of Bulgaria from Ottoman rule in 1878, Nesebar became part of the autonomous Ottoman province of Eastern Rumelia until it united with the Principality of Bulgaria in 1886.Around the end of the 19th century Nesebar was a small town of Greek fishermen and vinegrowers, but developed as a key Bulgarian seaside resort since the beginning of the 20th century. After the departure of the greeks in 1925 a new town part was built and the historic Old Town was restored.