Tallinn is the capital, the most populous city of Estonia. Located in the northern part of the country, on the shore of the Gulf of Finland of the Baltic Sea, it has a population of 437,619 in 2020. Administratively a part of Harju County, Tallinn is the main financial, industrial and cultural centre of Estonia; the second largest city, Tartu, is located in the southern part of Estonia, 187.2 kilometres (116.3 mi) southeast of Tallinn. Tallinn is located 80.32 kilometres (49.91 mi) south of Helsinki, Finland, 320.56 kilometres (199.19 mi) west of Saint Petersburg, Russia, 300.84 kilometres (186.93 mi) north of Riga, Latvia, and 380 kilometres (240 mi) east of Stockholm, Sweden. It has close historical ties with these four cities. From the 13th century until the first half of the 20th century Tallinn was known in most of the world by its historical German name Reval.