Dubrovnik is the southernmost major Croatian city. It is located on the Adriatic Sea coast. The walled city centre, known as the Old Town, is a site of historical monuments and heritage buildings largely dating to the Republic of Ragusa; the city has been placed on the list of UNESCO World Heritage Sites. In 1991, the city had a population of approximately 50,000, of whom 82.4% were Croats and 6.8% were Serbs. Croatian territory surrounding the city stretches from the Pelješac peninsula to the west and the Prevlaka peninsula in the east at the entrance to the Bay of Kotor on the border with Montenegro. This territory is very narrow, especially near Dubrovnik itself, and consists of a wide coastal strip of land.