Louis XIV's reign), the governor's house and the keep. Completely backfilled in the 17th century in order that cannons may be used, the original medieval soil is up to eight metres below the modern-day surface. Archaeological excavations have revealed a square tower which probably served as a watchtower which has been entirely buried underground. A second building protects the courtyard under which a dungeon can be found. This building is also protected by a drawbridge and portcullis. Only the two medieval towers remain as the rest (in particular the upper floor) were destroyed by cannon in the sixteenth century. The drawbridges of the two gatehouses are not on the same axis in order to hinder the manoeuvering of battering rams. The cistern The water cistern, with a capacity of 20,000 L, was expected to have been sufficient to serve the entire garrison (about forty men) although given the maximum retention volume seems limited. A rainwater recovery system was put in place. On the same level of the tank, a dummy drawbridge was intended to deceive any maritime attackers who would be deceived into sailing onwards an area of strong currents where their ship would then be at risk of smashing against the rocks. This dummy drawbridge was, however, ineffective. The cannons Eight cannons were installed during the reign of Louis XIV, the largest being eight metres long. Today, only "medium" copies are present on the site, but which could still shoot a ball up to a kilometre. Ballistic adjustments were made by use of the runway - a granite circle on which the cannon were placed and guided the wheels of the gun as it was manoeuvered into position. According to military records, one shot could be fired every three minutes. Oven to 'Blush' the balls The Chateau of the Roche Goyon also has a ball oven for heating cannonballs so that they were 'red-hot' prior to firing. The oven and method were rarely used however, for several reasons: the oven consumed a lot of wood; for this to be effective, it had to heat for eight hours, which gave the enemies plenty of time to flee; loading the cannon proved much more dangerous as the hot ball could cause to pre-ignite the black powder before the cannon could be properly fired. The use of ball ovens resulted in the coining of the expression "Tirer à boulets rouges" ("To shoot