Belém Tower was first built to defend Lisbon and later was transformed into a lighthouse and a customs center.
Was built in the sixteenth century by the Portuguese architect and sculptor Francisco de Arruda. It was classified as a World Heritage Site by UNESCO.
Each of the five floors are connected by a small and narrow spiral staircase, which, on the busiest days leads to having to wait your turn to climb and descend. The ground floor has 16 windows with cannons. The visit also includes a tour of the pits and holes where the prisoners were thrown into.