The Belém Tower was originally built to defend the Tagus estuary. This was part of a major program for the general reorganisation of earth and sea forces. It was a great plan and, for decades, there were no complaints from populations who in the past were victims of constant looting by corsairs and pirates.
The initial project included the Fortress of Cascais, the Old Tower on the south bank and in front of this, the Tower of Belém as fixed defensive measures. Equipped with sturdy bombards, the cross shot represented a formidable obstacle to all hostile vessels that tried to force entry into Lisbon. A ship of 1000 barrels was built, full of numerous pieces, complementing the defensive device with a mobile base of fire. And, because it was still considered insufficient, caravels equipped with powerful armament were built. These were in position, ready to intervene in case of need.
With the evolution of the attack and defense measures, its structure gradually lost its original defensive role. Over the centuries it was used as a customs registration, telegraph signalling station, lighthouse and even as a dungeon for political prisoners.
Initially surrounded by water in all its perimeter and, since 1983, classified as a UNESCO World Heritage Site. Belém’s Tower is undoubtedly one of the most expressive monuments of Lisbon.