The Torre de Belem is a tower built in the early 16th century in the Portuguese late Gothic style, the Manuline. It was built to commemorate Vasco da Gama's expedition and it is located in the Belem district of Lisbon. The Tower has become one of the symbols of the city and was classified in 1983 as a UNESCO World Heritage Site. The Belém Tower was constructed both as a ceremonial gateway to Lisbon and as part of a defence system of the entrance of the Tagus river and the Jerónimos Monastery, which was necessary to protect Lisbon. The tower itself, 35 metres high, has four storeys and a terrace, which is open for the public.