São Jorge Castle, former Paço de Alcáçova, is the castle to visit for those visiting Lisbon. Its first fortress dates back to the 1st century BC and it has been rebuilt several times by various peoples and given different names over time. The Castle of São Jorge is located on the highest hill in the historic centre, offering one of the most magnificent views over the city and the Tejo river estuary. The monument also comprises gardens, viewpoints, a podium, an esplanade, a darkroom, an exhibition space, a meeting/reception room and a thematic shop.