Cannon at the grounds of Castelo de São Jorge in Lisbon, Portugal. Saint George's Castle is a historic castle in the Portuguese capital of Lisbon, located in the freguesia of Santa Maria Maior. Human occupation of the castle hill dates to at least the 8th century BC while the first fortifications built date from the 1st century BC. The hill on which Saint George's Castle stands has played an important part in the history of Lisbon, having served as the location of fortifications occupied successively by Phoenicians, Carthaginians, Romans, and Moors, before its conquest by the Portuguese in the 1147 Siege of Lisbon.