The imposing Château de Bonaguil is spectacularly perched on a wooded spur downstream from Cahors. Dating largely from the fifteenth and sixteenth centuries, with a double ring of walls, five huge towers and a narrow boat-shaped keep designed to resist artillery, Bonguil was the last of a dying breed, completed just when military architects were abandoning such elaborate fortifications. As it attracts around two thousand visitors a day during summer, it’s advisable to get here early.