The Castle of the Moors is a ruined medieval fortification on the ridge above Sintra, built during the Moorish occupation of the Iberian Peninsula. The walls snake along the rocky ridgeline for several hundred metres, and walking the ramparts offers some of the best views in the Sintra area: down to the town and the National Palace below, across to the yellow towers of Pena Palace next door, and on a clear day all the way to the Atlantic coast.
The castle is less crowded than Pena Palace and takes about an hour to walk properly. The stone walls are largely intact from the medieval period, with the towers and gates restored in the 19th century. There is no roof or interior — this is a walls-and-views attraction, and a very good one. Wear shoes with grip; the rampart paths are uneven and can be slippery in wet weather.