Portugal, is a country on the Iberian Peninsula in Southwestern Europe. Featuring the westernmost point in continental Europe, Portugal borders Spain to its north and east, with which it shares the longest uninterrupted border in the European Union; to the south and the west is the North Atlantic Ocean; and to the west and southwest lie the Macaronesian archipelagos of the Azores and Madeira, which are the two autonomous regions of Portugal. Lisbon is the capital and largest city, followed by Porto, which is the only other metropolitan area. The western Iberian Peninsula has been continuously inhabited since prehistoric times, with the earliest signs of settlement dating to 5500 BC. Celtic and Iberian peoples arrived in the first millennium BC.