The Castelo de Sao Jorge (St. George's Castle), the name comes from the time of King Joao I ( late 14 century) Before it was known simply as Lisbon Castle. 

It consist of the former citadel of Alcazar, twelve gateways (seven of which lead to the parish of Santa Cruz do Castelo), the battlements and wall of Barbeca (Barbican) and eighteen towers (eleven of which belong to the fortress, and one, Torre de Sao Lourenco, is linked to the battlements by a long stairway. If we go though Portao Sul (the south gate) which leads to Rua de Santa Cruz do Costelo, we enter the old Praca de Armas. 

After a short period of splendor in the reign of King Sebastiao, who hat it restores and went to live there, the royal palace on the site of the castelo fell into complete neglect during the reign of the Spanish kings and was used as a barrack and later as a prison. 

The building was severely damages by the 1755 earthquake. 

In 1910 the building was declared a National Monument and restoration work began.