The harmony and delicate ornamentation of the Tower of Belém suggests a finely cut jewel to all laying eyes on her. However, its contemporaries took a rather different perspective: a formidable and imposing bastion defending the entrance to the Tagus and capable of combining firepower with the St Sebastian tower on the other bank of the river. Its construction was ordered by king Manuel I (1495-1521) and it was built by Francisco de Arruda between 1514 and 1521. The tower was built on a basalt island that was close to the right bank of the Tagus in front of Restelo beach. However, with the gradual change in the course of the river, the tower has ended practically swallowed up by the bank.