[1] For the first several centuries of its existence, the Château de Billy was the property of its builders, the Bourbons.
The fortified town of Billy and the province of Bourbonnais were part of the domain of the lordship of the Bourbons.
The main fortification has an ovoid layout with a hexagonal watchtower which dominates the houses of the town and the medieval streets that curve around the walls of the castle.
The southern curtain wall has a walkway that offers a splendid panorama of the Allier valley.
It has been listed since 1921 as a monument historique by the French Ministry of Culture.