Castle Saint-Étienne is a medieval fortress located on an elevated hilltop in Aurillac, Cantal, dating to the 9th century when it was established as a military castrum under Count Gérald, father of Saint Géraud. The castle features a medieval square tower and buildings rebuilt in the 19th century by architect Just Lisch, representing multiple construction phases from the 12th and 14th centuries. Captured by Aurillac's inhabitants in 1233 and occupied by English forces during the Hundred Years' War, it later served as a teacher training college from 1845 to 1940. Now listed as a historic monument, the castle houses the Muséum des Volcans and municipal offices, providing visitors access to exhibits exploring volcanic phenomena alongside this significant medieval landmark.