Château de Mauzun, Medieval fortress in Mauzun, France.

Château de Mauzun is a medieval fortress whose black walls spread across a large site and are defined by numerous defensive towers built from local volcanic stone. The complex consists of multiple stone structures that remain partially in ruins today.

The fortress was originally founded by the Counts of Auvergne but transferred to the Bishops of Clermont in 1207 to prevent seizure by the French crown. This shift in control shaped the site's long-term history.

The castle's name comes from the village it overlooks, and its black volcanic stone was quarried on the volcano itself. In 1589 it served as headquarters of the Catholic League in Auvergne under Bishop François de la Rochefoucauld, who submitted to the king the following year and kept Mauzun. Visitors today see the ruined towers and curtain walls on the grassy mound.

Visits to the castle were stopped after the 2019 Covid crisis and the site is no longer accessible, so it cannot be entered or explored. The ruins stand on an overgrown grassy mound above the village of Mauzun, on the volcanic butte that the fortress was built around. The remains can only be seen from a distance.

The building materials came directly from the volcano on which the castle stands, giving the stone blocks a distinctive black color. This characteristic makes the fortress instantly recognizable in the landscape.