Croatia is shaped like a horseshoe, stretching from Vukovar in the northeast, past Zagreb in the west, and to Dubrovnik in the far south. It gained most of its present-day contours at the end of the 17th century. With a surface area of 56,594 km², it is 19th among the European Union countries according to size. In terms of relief and climate, it is extremely diverse. The territory includes extensive plains in the continental region between the River Drava and River Sava (Slavonia), mountainous areas in the centre (Lika and Gorski Kotar) and, in the west and south, a long, indented, sunny coastline with over a thousand islands (Istria and Dalmatia). Croatia belongs to the Danube Basin and the Adriatic Sea and forms the Mediterranean front of Central Europe, positioned favourably in terms of geography and communications at the meeting point of important European corridors, while its harbours are used as sea exits by the neighbouring countries to the north.