The Moorish Castle is strategically located on one of the top hills of Sintra to defend both the local territory and the maritime access to the city of Lisbon. The castle was built around the 10th century by the Muslim populations that occupied the Iberian peninsula. The castle acted as a control tower for the Atlantic coast and the land to the north, mostly serving as an outpost for the city of Lisbon. The castle's Muslim rule ended in 1147 when King Afonso Henrique conquered Lisbon. In 1995, UNESCO listed Sintra hills as a Cultural Landscape, World Heritage, including the Moorish Castle. Highly recommended to climb and walk along the walls of the castle, carved out of the rock, to have a panoramic view over Sintra and its castles and palaces.
Though you'd have to sometimes stop and catch your breath along the way, this is pretty much a leisurely trek up to the castle walls. It’s a piece of 9th century history on a mountain top, where one wonders how, without today’s modern machineries, this could have been engineered.