This castle was successively a military fortress - taken by Charlemagne in 778 (legend), a state prison, the residence of the counts of Bigorre in the 16C and 17C, and has undergone numerous transformations with the passing years: donjon from the 14C, drawbridge restored in the 19C…
However it has been an important military post and remarkable witness to the evolution of fortresses in the Pyrenean Piedmont, from the Middle Ages to our time.
Only lapidary vestiges remain from the Roman times; of cultural interest only: head and hands of funerary statues, fragments of an altar with an inscription. From the Romanesque period (11C-12C) remain parts of walls with small cubic bond and average-sized regular ranged bond: sides of the southeast and southwest parts of the upper wall.
During the Gothic period (13C-15C) the castle was arranged in three successive lines of defence: the lower wall encircling the rock on which it is built, the castle with its bastioned upper wall and lastly the donjon.
At the time of Febus, the castle was commanded by Pierre Arnaud de Béarn, and then Jean, his brother, both cousins to the Prince of Béarn, with the help of 39 mercenaries (Compagnons de Lourdes), who signed in 1379, an agreement with the prince stipulating that any money and «prizes» in kind (wine, wheat) that might be received from the people of Bigorre had to be shared, in exchange of his «protection».
Later on, following the Wars of Religion (16C) and the 17C earthquakes, the castle was greatly restored: Vauban’s projects (1685), and modifications by the military Engineers (1828-1856) have given it its present appearance.