Castillo de sao Jorge

 I found Rick Steves's  snapshot of Lisbon booklet very helpful and at times I’m quoting from what he says. His descriptions of museums and castles, etc. are much better than perhaps the lengthy descriptions that you get if you take a tour guide or an audio guide. 

The Castelo de Sao George dates to the 11th century, when the Moors built it to house their army and provide a safe haven for the elites in times of siege. After Alfonso Henriques took the castle in 1147, Portugal’s royalty lived here for several centuries. The sloping walls typical of castles from this period were designed to withstand 14th century cannonballs. In the 16th century, the kings moved to their palace on Praca do Comercio, and the castle became a military Garrison. Despite suffering major damage in the 1755 earthquake, the castle later served another stint as a military Garrison. In the 20th century it became a national monument. 

I walked up to the castle which is high above the city but took the bus back down to the centre of the city near my hostel.