Perhaps Belém's most famous feature is its tower, Torre de Belém, whose image is much used by Lisbon's tourist board. The tower was built as a fortified lighthouse late in the reign of Dom Manuel l (1515–1520) to guard the entrance to the port. It stood on a little island on the right side of the Tagus, surrounded by water. Belém's other major historical building is the ''Mosteiro dos Jerónimos'' (Jerónimos Monastery), which the Torre de Belém was built partly to defend. Belém's most notable modern feature is the Padrão dos Descobrimentos (Monument to the Discoveries) built for the Portuguese World Fair in 1940. In the heart of Belém is the ''Praça do Império'': gardens centred upon a large fountain, laid out during World War II. To the west of the gardens lies the ''Centro Cultural de Belém''. Belém is one of the most visited Lisbon districts. Here is located the Estádio do Restelo, house of Belenenses.