Castelo São Jorge is a Moorish Castle occupying a commanding position over the city of Lisbon and the River Tagus. Archaeological evidence suggest there has been a fortified position on this site since Celtic times.
The current, reconstructed castle is based on the 11th century building created during the introduction of christianity to Portugal and the ousting of the previous Moorish rulers in 1147.
Alfonso Henriques, later King Alfonso 1 of Portugal, led the second crusade to drive the Moors from Lisbon and surrounding areas. Fearing a counter attack, he upgraded the defences of the castle.
The castle provides spectacular panoramic views over the city and the river as a reward for the fairly steep walk up. The number 37 minibus drops off right next to the castle if you wish to avoid the walk uphill.