The Duchy of Bouillon () (), a small state located between Luxembourg, Champagne, and the Three Bishoprics and centered on Bouillon. The duchy was claimed by the House of La Tour d'Auvergne. It was officially a State of the Holy Roman Empire. Even though it was a fairly small "state" its capital was the city of Bouillon, now in modern Belgium. The La Tour d'Auvergne family claimed to rule the state from 1456? – 1794 as during the French Revolution it officially changed its legal status to the "". The heir to the ducal throne was traditionally titled the Prince of Turenne. 