Italy, officially the Italian Republic, is a country in Southern and Western Europe. It consists of a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land border, as well as nearly 800 islands, notably Sicily and Sardinia. Italy shares land borders with France to the west; Switzerland and Austria to the north; Slovenia to the east; and the two enclaves of Vatican City and San Marino. Italy shares a maritime boundary with Croatia, Montenegro, Albania, Greece, Libya, Malta, Tunisia, Algeria and Spain. It is the tenth-largest country in Europe by area, covering 301,340 km2 (116,350 sq mi), and the third-most populous member state of the European Union, with nearly 59 million inhabitants. Italy's capital and largest city is Rome; other major cities include Milan (the largest metropolitan area in the country), Naples, Turin, Palermo, Bologna, Florence, Genoa, and Venice. The history of Italy goes back to numerous Italic peoples, notably including the ancient Romans, who conquered the Mediterranean world during the Roman Republic and ruled it for centuries during the Roman Empire. With the spread of Christianity, Rome became the seat of the Catholic Church and the Papacy. Barbarian invasions and other factors led to the decline and fall of the Western Roman Empire between late antiquity and the Early Middle Ages. By the 11th century, Italian city-states and maritime republics expanded, bringing renewed prosperity through commerce and laying the groundwork for modern capitalism.