The castle of Sedan dominates the Meuse river. With its 8.64 acres (35,000 m²) over seven floors, it is sometimes considered the largest fortress of medieval origin in Europe. It stands on walls 22 to 88.5 ft wide (7 to 27 m). The castle built in 1424 remained the property of the princes of Sedan until the unification of the principality with France in 1642. It served as a fort for the French armies until 1962. The castle was meant to be dismantled, but the city of Sedan bought it from the French army and turned it into a medieval museum.