Castelo de Almourol
Constacia is a small town that has a great castle and very important for Portuguese history.
Its the castelo de Almourol.
I visited it long time ago. Back in 1997 I went camping right on the island where the castle is constructed. I went with my friends from Kung-Fu classes. Very nice scenery to practice some martial arts I say.
This fortress is located around Tomar, the old Templiers city. It is built on an island of Tage the 310 meters length, 75 meters broad and 18 meters at the highest point. Fortress Moor, the castle of Almourol was taken again at the time of the Portuguese reconquista under the reign of Alphonse 1st. In 1171, the castle was entrusted to the temple which decided to rebuild it to make of it a watchtower of the kingdom of Portugal. Besieged in 1190 by the Moors, it resisted. Thereafter, its role of border post disappeared because of advanced from the catholic armies. It was never taken.
The castle is accessible by boat because it is truly an island: there are frontier runners which with the help of a moderate entrance fee enables you to reach it. The sight of in top is exceptional. Since you are in the area, do not forget either to pass by Tomar whose Templiers site with its castle and its cloisters is classified world inheritance of humanity.