Also called the Tower of St Vincent, Belem Tower is a fortified tower which is located in the civil parish of Santa Maria de Belem. It was built in the early 16th century by King John II designed to act as defence system. Belem Tower sits magnificently at the mouth of the Tagus river as a ceremonial gateway to enter Lisbon. It was built from lioz limestone and composed of a bastion and a 30-metre, four-storey tower. Together with the nearby Jeronimos Monastery, it is classified as a UNESCO World Heritage Site.