I was supposed to visit this castle in Montemor-o-Velho yesterday but i really needed to spend a day off at home and decided not to go. Now i might visit it next week.
"Above the town are the forbidding ruins of its massive castle, at one time amongst Portugal's strategically most important fortresses. Nothing remains of the original castle, first mentioned in 716 when occupied by the Moors. The existing ruins date from the 11th and 12th C. and are enclosed within a double circuit of walls, oval in plan, with imposing towers and battlements.
From the top of the towers, some of which can be climbed, there is a superb view over the surrounding countryside. Within the walls is the Manueline church of Santa Maria de Alcáçova (16th C.) by the famous architect Boytaca, with a beautiful wooden ceiling, azulejo decoration in 16th C. Moorish style and a double font." - in: http://www.planetware.com/montemor-o-velho/castelo-p-coim-cast.htm