Sedan Castle, also known as Château de Sedan in French, is a fortress located in the town of Sedan in the Ardennes region of northeastern France. It is one of the largest and best-preserved castles in Europe.

The castle was constructed in the 15th century by the powerful La Marck family, who were known for their military prowess. Over the centuries, it was expanded and improved upon by various owners, including the Prince de Condé, who added a grand staircase and ornate furnishings.

The castle played an important role in the religious wars of the 16th and 17th centuries, and was besieged several times. In 1642, during the Thirty Years' War, it was successfully defended against a Spanish siege by a small garrison led by the famous French military engineer Vauban.

Today, the castle is open to visitors and offers guided tours of the various rooms and galleries, including the 17th-century Grand Salon, the chapel, and the armory. Visitors can also climb to the top of the keep for panoramic views of the surrounding countryside.