Nesebar (other spellings include Nessebar and Nesebur) is an ancient city and a major seaside resort on the Black Sea coast of Bulgaria, located in Nesebar municipality, Burgas Province. Often referred to as the "Pearl of the Black Sea" and "Bulgaria's Dubrovnik", Nesebar is a rich city-museum defined by more than three millennia of ever-changing history. It is a one of the most prominent tourist destinations and seaports on the Black Sea, in what has become a popular area with several large resorts—the largest, Sunny Beach, is situated immediately to the north of Nesebar. Nesebar has on several occasions found itself on the frontier of a threatened empire, and as such it is a town with a rich history. The ancient part of the town is situated on a peninsula (previously an island) connected to the mainland by a narrow man-made isthmus, and it bears evidence of occupation by a variety of different civilisations over the course of its existence. Its abundance of historic buildings prompted UNESCO to include Nesebar in its list of World Heritage Sites in 1983.