The first known document that testify of the existence of Bonaguil dates back to 1271. It establishes the taking up of l’Agenais by Philippe III the Bold, King of France. The stronghold is then embellished with a plain stone tower, foundation of the current dungeon. Towards the beginning of the 15th century, a second building campaign confer the present aspect of this castle. The first meagre dwelling is added.
Then comes the powerful Bérenger of Roquefeuil (1448-1530) from the aristocracy of Quercy and Rouergue who will dedicate thirty years of its own life to make of Bonaguil the legendary fortress we know nowadays. He provides the fortified castle with an enormous barbican, composed of six towers which one of them is one of the most beautiful in the country, then there are seven drawbridges, one chicane, one pillbox, gunboats and one sparrow house full of loopholes that enable a defense even more incisive of the ditches.
The fortress is modified again in the second half of the 18th century by Marguerite of Fumel.
She arranged the construction of a plaza, the suppression of the drawbridges and the update remodeling of apartments for lords.
She passed away shortly before the French revolution that turns out tragic for the castle: a 1793 law gave the order to chop down the constructions up to the main building and to behead the towers. Metal window frames and wood materials had been removed and the dwelling had been plundered and abandoned to its fate.
Fumel municipality acquired Bonaguil in 1860 and classified the property as Historic Monument as of 1862. The municipality works as a sponsor for the castle nowadays by opening Bonaguil to a large number of visitors each year.