Torre di Federico is an octagonal ancient tower that was allegedly a summer residence of Frederick II of Hohenstaufen. The two floors possess beautiful vaults. The aspect of the building is austere. It was part of a bigger complex, named Old castle and destroyed by Arabs. Remnants include some pieces of the old, imposing walls on the top of the green hill where the Tower rises.
The tower is an imposing 26 metres high, has a diameter of 17 metres and its walls are 3.5 metres thick.
The Château de Foix dominates the town of Foix. An important tourist site, it is known as a centre of the Cathars. Built on an older 7th-century fortification, the castle is known from 987. In 1002, it was mentioned in the will of Roger I, Count of Carcassonne, who bequeathed the fortress to his youngest child, Bernard. In effect, the family ruling over the region were installed here which allowed them to control access to the upper Ariège valley and to keep surveillance from this strategic point over the lower land, protected behind impregnable walls.
In 1034, the castle became capital of the County of Foix and played a decisive role in medieval military history. During the two following centuries, the castle was home to Counts with shining personalities who became the soul of the Occitan resistance during the crusade against the Albigensians.