Seat of the count and symbol of accounts, it is a place strongly linked to Catharism.

The present fortifications on the rock probably preceded the Castle of Foix. The Ciutadella has been mentioned since 970, but it was after the creation of the Comptat, in 1002, that the castle took on its current appearance, with the construction of the two square towers. The round tower is later and dates from the 15th century.

The Crusade did not attempt to storm this castle, and it did not suffer a siege either. The Count of Foix placed his fortress in the hands of the Pope as an act of submission, at the Lateran Council, in 1214. It was transformed into a prison in the 17th century and later, in the 19th century, it was restored to its current medieval appearance.