Malta, formally known as the Republic of Malta and formerly Melita, is a Mediterranean island nation in southern Europe that consists of an archipelago. It can be found 80 kilometers south of Italy, 284 kilometers east of Tunisia, and 333 kilometers north of Libya. Malta is the world's tenth smallest nation in terms of area and fourth most densely populated sovereign country, with a population of around 515,000 people spread over 316 km2. Valletta, the country's capital, is the smallest national capital in the European Union, with an area of 0.61 km2. Maltese is the official and national language, and English is the second official language. Maltese is derived from Sicilian Arabic, which originated during the Emirate of Sicily. For centuries, Italian and Sicilian acted as official and cultural languages on the island, with Italian serving as an official language in Malta until 1934 and a majority of the current Maltese population speaking Italian at least conversationally. Since approximately 5900 BC, Malta has been inhabited. With a succession of forces contesting and ruling the islands, including the Phoenicians and Carthaginians, Romans, Greeks, Arabs, Normans, Aragonese, Knights of St. John, French, and British, its position in the heart of the Mediterranean has traditionally given it great strategic significance as a naval base. The majority of these outside forces have left their imprint on the country's ancient culture. Malta became a British colony in 1813, and it served as a shipping port and headquarters for the British Mediterranean Fleet. During World War II, it was besieged by the Axis powers and served as a vital Allied base for operations in North Africa and the Mediterranean. The Malta Independence Act of 1964, passed by the British parliament, granted Malta independence from the United Kingdom as the State of Malta, with Queen Elizabeth II as its head of state and queen. In 1974, the nation became a republic. Since independence, it has been a member of the Commonwealth of Nations and the United Nations, and in 2004 it entered the European Union; in 2008, it joined the eurozone monetary union. Malta has had Christians since the early Christian era, though it was mainly Muslim during the period of Arab rule, when Christians were tolerated. With Roger I's Norman invasion of Malta in 1091, Muslim rule came to an end. Malta is a tourist destination with its warm climate, various recreational areas, and architectural and historical monuments, including three UNESCO World Heritage Sites: al Saflieni Hypogeum, Valletta, and seven megalithic temples that are some of the oldest free-stand structures in the world.