The Citadel of Blaye is a 17th-century fortress in the town of Blaye north of Bordeaux, France. Due to Blaye's strategic location on the Gironde estuary, King Louis XIV ordered the Marquis de Vauban to build the fortress in order to protect Bordeaux from attack. The citadel is a walled city that covers an area of about 94 acres and was built around a parade ground, a monastery dedicated to the Minims order, and several army barracks. The ruins of many buildings are inside the fortress, including the 12th-century Rudel Castle, the 12th-century Liverneuf Gate, and the 15th-century Éguillette Tower.
At the time when the Citadel of Blaye was built, the range of the cannons was not long enough to cover two miles from one side of the river to the other. Vauban built two more forts, Fort Paté and Fort Médoc, so that the three together could set up cross-fires to prevent enemies from reaching Bordeaux.