Château d'Allègre, Medieval castle ruins in Allègre, France.

The Château d'Allègre is a ruined castle in Allègre, Haute-Loire. Its remains are two corner towers of the former keep, joined by a section of machicolation and a round walk, plus the base of a tower in the enceinte. The taller tower is pale rough-cut stone with a projecting crenellated crown; the other is thicker and darker, of mixed stone.

Built at the end of the 14th century by Morinot de Tourzel, a favourite of the Duc de Berry, to plans by Hugues Aubriot, architect of the Bastille, the castle was the seat of the second barony of Auvergne and had three fortified enceintes. It withstood sieges during the Hundred Years' War and again in 1593 in the war against the Catholic League, before burning down on 15 November 1698.

The castle was the seat of the second barony of Auvergne, held by Morinot de Tourzel, a favourite of the Duc de Berry. Its name comes from the commune of Allègre in the Haute-Loire. Since the French Revolution the commune has owned the ruins and quarried them for building stone.

The ruins stand on the hill of Allègre in the Haute-Loire; the site is unprotected open ground, so watch for uneven footing and loose stones. The two keep towers and the section of machicolation and round walk are the standing elements; the base of the enceinte tower lies lower down. The castle has been a monument historique since 1935.

The castle was the seat of the second barony of Auvergne, and its builder Morinot de Tourzel was a favourite of the Duc de Berry. The plans were drawn up by Hugues Aubriot, the architect of the Bastille. Since the French Revolution the commune has owned the ruin and quarried it for building stone.