The Republic of Lithuania founded in 1918 and located on the eastern shore of the Baltic Sea. The southernmost and largest of the two Baltic Republics – Estonia and Latvia. Lithuania was a powerful empire that dominated much of eastern Europe in the 14th–16th centuries before becoming part of the Polish-Lithuanian confederation for the next two centuries. Lithuania has The Curonian Spit is 98 kilometres (61 miles) long, thin, curved sand-dune spit that separates the Curonian Lagoon from the Baltic Sea coast. Human habitation of this elongated sand dune peninsula dates back to prehistoric times. Its southern portion lies within Kaliningrad Oblast, Russia and its northern within southwestern Lithuania. It is a UNESCO World Heritage Site shared by the two countries.