Belém Tower

This guide to Belém Tower in Lisbon starts with King Manuel I's boast: a fortress raised around 1514, carved with stone ropes and a rhinoceros, to declare Portuguese command of the sea after Vasco da Gama's voyage to India. It follows the tower's turn from monument to prison after Spanish forces swept into Portugal in 1580, when political prisoners were held in a chamber at river level. Listen for how the rising tide reached them.