Kaliningrad (known as Königsberg until 1946) is the largest city and administrative centre of Kaliningrad Oblast, an exclave of Russia between Lithuania and Poland (663 kilometres (412 mi) west of the bulk of Russia). Located on the Pregolya River at the head of the Vistula Lagoon, it is the only ice-free Russian port on the Baltic Sea. Its population in 2020 was 489,359. Kaliningrad is the second-largest city in the Northwestern Federal District, after Saint Petersburg and the seventh-largest city on the Baltic Sea.
The city had been founded in 1255 on the site of the ancient Old Prussian settlement Twangste by the Teutonic Knights during the Northern Crusades, and named Königsberg ("king's mountain") in honor of King Ottokar II of Bohemia. A Baltic port city, it successively became the capital of the State of the Teutonic Order, the Duchy of Prussia and the provinces of East Prussia and Prussia. From 1454 to 1455, the city under the name of Królewiec belonged to the Kingdom of Poland, and from 1466 to 1657 it was a Polish fief. It was the coronation city of the Prussian monarchy, though the capital was moved to Berlin in 1701. Königsberg was the easternmost large city in Germany until World War II.