The original castle was built by the Trencavels - Viscounts of
the Razès - in the twelfth century.
Later in the twelfth century, the lordship of Coustaussa belonged
to the Vilar family. Soon after, it was in the hands of the de Fenouillet
family. In 1367, by the marriage of Geraude de Fenouillet to Saix
de Montesquieu, the lordship passed to the Montesquieus who kept
it until the French Revolution.
On their way back from Termes
in late November 1210, Simon
de Montfort and his Crusaders found the Château at Coustaussa
already abandoned, and so carried on to Puivert.
Apparently the garrison at Coustaussa, like the one at Le
Bézu had lost heart after the fall of Termes.
Like many other strongholds Coustaussa returned to its traditional
allegiance the following year. According to the Historia
Albigensis , Simon
de Montfort was at Narbonne with a crowd of newly arrived Crusaders
when he heard the news. He immediately hurried off to Coustaussa
and attacked it. The castle was surrendered after "a few days",
after which Simon set off for Castelnaudry.
After the Crusades, the Castle came into the possession of the
de Montesquieu family.
present Château was apparently still in good shape until the
nineteenth century, when an enterprising local realised that he
could turn a few Francs by stripping out and selling the woodwork.
During the night of 31 October to 1 November 1897, the parish priest
of Coustaussa, the Abbé Antoine Gélis, was brutally
murdered in his presbytery. The crime was not solved. The Abbé
was found during the investigation to possess large sums of money
which had not been taken by his assailants. This event has been
incorporated into the Rennes-le-Chateau "mystery". (Rennes-le-Chateau
is in sight of Caustaussa across the Salz valley.