The city of Chania can be divided in two parts: the old town and the modern city which is the larger one. The old town is situated next to the old harbour and is the matrix around which the whole urban area was developed. It used to be surrounded by the old Venetian fortifications that started to be built in 1538; of them the eastern and western parts have survived. From the south, the old town is continuous with the new, and from the north the physical border is the sea. The centre of the modern city is the area extending next to the old town and especially towards the south.