Humans settled on this hill as early as the 8th century BCE, and the first fortifications date from the 1st century BCE. Before the Portuguese conquest in the 1147 Siege of Lisbon, the site was successively occupied by the Phoenicians, Carthaginians, Romans, and Moors. Sights within the castle include the permanent exhibition of archaeological artefacts with an emphasis on the 11th- and 12th-century Moors, ruins of the former Royal Palace of Alcáçova, a garden with native forest species, and a camera obscura showing the city's sights. The castle offers great view over the city and the river. If you have the energy, get there by walking from downtown, going through the fantastic old neighbourhood of Alfama.