Montenegro is a country in Southeastern Europe, located on the Adriatic Sea, sharing borders with Serbia to the northeast, Bosnia and Herzegovina to the north and west, Albania to the southeast and Croatia to the southwest. Podgorica is the capital and largest city, covers 10.4% of Montenegro's territory of 13,812 square kilometres (5,333 sq mi), and is home to roughly 30% of its total population. The name Montenegro was first used to refer to the country in the late 15th century. Montenegro's independence was recognized by the Great Powers at the Congress of Berlin in 1878. In 1910, the country became a kingdom. After World War I, it became part of Yugoslavia. Following the breakup of Yugoslavia, the republics of Serbia and Montenegro together proclaimed a federation. Following an independence referendum held in May 2006, Montenegro declared its independence.