The Castelo dos Mouros (Castle of the Moors) in situated on the hills around Sintra. It was built in the 9th century, when Portugal was under moorish rule. This day it's in ruins... my guidebook actually describes it as a "romantic ruin"! Since we had lots of other things we wanted to do in Sintra we didn't go visit the ruins themselves, but here are a couple of photos taken from below the hills and the entrance.
Ahí en la distancia, en la cima de la colina, el castillo.
There in the distance, right at the top of the hill, the castle.
Y un zoom-in, lo más que pude con mi cámara.
And a close-up, the best I could do with my camera.
La entrada, en la colina.
The entrance, right up the hill.