East Prussia
East Prussia (German: Ostpreußen [ˈɔstˌpʁɔɪ̯sn̩] ) was a province of the Kingdom of Prussia from 1772 to 1829 and again from 1878, with the Kingdom itself being part of the German Empire from 1871; following World War I, it formed part of the Weimar Republic's Free State of Prussia until 1945. Its capital city was Königsberg (present-day Kaliningrad, Russia).