Medieval Louvre Castle

Deep beneath the modern museum’s glass pyramid lies the masonry of the Medieval Louvre, a fortress built by King Philip the Second in eleven ninety. To protect Paris from invasion, he raised a square of thick stone walls around a central, thirty-meter-high keep known as the Grand Donjon. This stronghold held the royal treasury and anchored the city’s western defenses, with a water-filled moat keeping guard against those arriving from the Seine.