allinn is the capital and largest city of Estonia, and lies on the southern coast of the Gulf of Finland. It is the closest capital city to capitals of Finland (Helsinki, 80km), Latvia (Riga
, 315km) and Sweden (Stockholm, 380km). In 1050 the first fortress was built on Toompea, a limestone hill in the central part of Tallinn. The foot of the hill lies at 17–20 m above sea level. In 1154 the city was first recorded on a world map of the Almoravid by the Muslim cartographer Muhammad al-Idrisi. In 1219, Tallinn was conquered by Valdemar II of Denmark, but it was soon sold to the Hanseatic League in 1285. The city was known as Reval from the 13th century until the 1920s. Tallinn’s historic center has been astonishingly well preserved and was inscribed on the UNESCO World Heritage Sites in 1997.