The Torre de Belém is undoubtedly Portugal's most iconic monument. The tower was built in the sixteenth century in the Tagus River to control the entrance to the city from the sea. The idea to build a fortress near Belém was launched in the fifteenth century by King John II, who commissioned the construction of a tower in the river Tagus as part of a larger defensive structure. By the time plans for the tower were completed, the King had died and the project was shelved. The project was revived in 1514, during the reign of his successor, King Manuel I. A new design was created for the fortified tower by Francisco de Arruda and construction started the following year near the harbor of Belém, the starting point of many of the Portuguese explorers during the Age of Discoveries. The tower was completed just six years later, in 1521. For a fortress, the tower has a surprisingly rich exterior with beautiful sculpted balconies and fine limestone ornaments, a testament to the wealth Portugal experienced during the Manueline era. The tower of Belém is something you have to see when you visit the city of Lisbon. Many restaurants are located close to the tower and the memory is lasting.