Portugal is the westernmost country of mainland Europe. Portugal is bordered by Spain to the north and east and by the Atlantic Ocean to the west and south. The Atlantic archipelagos of the Azores and Madeira are also part of Portugal. During the 15th and 16th centuries, with its vast transcontinental empire, Portugal was one of the world's major economic, political, and cultural powers. Portugal is a member of the European Union (since 1986), the United Nations (since 1955), and a founding member of the Eurozone, OECD, and NATO.