The town-fortress called Nessebar /Mesembria/ is one of the most ancient cities in Europe. It was founded on a rocky peninsula 850m long and 300m wide. The area is around 25 ha and is connected with the main land through a narrow embankment, a road 400m long. The first inhabitants on the peninsula – the Thracians, started the fortification of the settlement in the 8th century BC. As seen the remained wall today is 2 m high. The best-preserved part of it can be seen today near the city gate, opposite to the strip. Two gates – a drawbridge like one and a twin leafed gate closed tightly the access to the town. During the Early Byzantine period a fortified wall was built on the south – west coast, near the port. After the town fell under the Ottoman yoke in 1453, the defence system lost its strategic importance and, left without any special cares and gradually declined.