Built in the second half of the 14th century, the Tour du Prince Noir (Black Prince's Tower) was a lighthouse which, like Sauron's eye at the top of Barad-dûr ("Dark Tower" in Sindarin), lit up the night with a continuous fire.

The lighthouse, octagonal in shape and rising 16 metres above the Cordouan plateau, was built by the Black Prince, Edward of Woodstock, son of King Edward III of England and Queen Philippa of Hainaut, at the height of the Hundred Years' War. It preceded the Cordouan lighthouse as we know it today.

The Black Prince's actions were not as murderous as those of Sauron in the universe of the British writer J.R.R. Tolkien. However, the Prince was known to have a penchant for violence, particularly after the Battle of Crécy, where he almost lost his life to a French knight and decided to take revenge by ordering the execution of all wounded French soldiers unable to pay ransom.

Having failed to respect the spirit of chivalry, and greatly disappointed his father the king, he decided to wear black armour, which gave him his nickname.

But if the life of the Black Prince would easily place him as an antagonist in Tolkien's universe, notably for his habit of going on rides to plunder his neighbours, as well as his own lands. He is still a long way behind the abominable Sauron, whose terrifying eye constantly watches over Mordor like the light of a lighthouse.

The Tour du Prince Noir was built in the second half of the 14th century, on the Gironde Estuary in Guyenne, in what is now Nouvelle-Aquitaine (France). The area, occupied by the English at the time, was the scene of numerous conflicts between the French and English kingdoms, as the Capetians and Valois (Kings of France) clashed with the Plantagenets (Kings of England) in the Hundred Years' War from 1337 to 1453.

After the end of the conflict, when Guyenne was definitively left to the Kingdom of France, the lighthouse passed into French territory. But its management did not really change. It was occupied by hermits, who were responsible for maintaining the fire and lived in the outbuildings of the chapel adjoining the lighthouse, dedicated to Notre-Dame de Cordouan.

The fire was maintained throughout the 15th century. However, the deteriorating state of the Tower from the mid-sixteenth century onwards prompted the hermits to stop maintaining the fire, as they refused to climb it. The numerous shipwrecks that followed prompted Jacques II Goyon, Marshal of Matignon and Governor of Guyenne, to report the matter to King Henry III of France. 

On 2 March 1584, the engineer-architect Louis de Foix was commissioned to build the Cordouan lighthouse to replace the Tour du Prince Noir. At the end of the work, twenty-seven years later, the remains of the Tower were washed away by the sea, after the devices built to protect the site and the workers had been removed.

So it was not the destruction of the Ring of Power that was responsible for the collapse of the Tour du Prince Noir, but time itself. And if Barad-dûr is swept away by the flames of Mount Doom, the terrible volcano of Mordor, in Tolkien's work, it was the sea that swept away what was left of the Tour du Prince Noir in the Gironde estuary in 1611, in reality.