Moulin Bleu, Historic mill in Bourgueil, France.

Moulin Bleu is a mill building in Bourgueil distinguished by its unusual form: a circular stone structure rising from an earthen mound, topped with a barrel vault and an open cone-shaped cupola. The elevated setting and geometric shape made it visible from across the valley.

Built in the 12th century, the mill was originally operated by Benedictine monks from Bourgueil Abbey to grind grain for local needs. In 1873, its purpose shifted when it began processing bark for the leather-tanning industry instead.

The name Moulin Bleu ("Blue Mill") is tied to the site's long use by the Benedictine monks of Bourgueil Abbey, who first ground grain here in the 12th century. After 1873 the mill was turned to grinding bark for tanning leather, a trade that marked the building's interior with the wear of a different kind of stone.

The mill stands on a raised mound reached from Route du Moulin-Bleu, a short walk or drive from the centre of Bourgueil. The ground around the base is uneven and the slope up the mound is unpaved, so sturdy shoes help. As an inscribed monument historique, the building itself is not open as a regular visitor site; view it from the road and respect any barriers.

The concrete poured by German forces during World War II was not laid on the vault but inside it, filling the barrel-vaulted chamber to create a platform for an anti-aircraft position on the mound. The flat slab now visible at the top of the structure is that wartime fill, not the original 12th-century masonry.