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Origin and history

The Greniers de César, located in Amboise on the left bank of the Loire, are a set of twelve wine cellars and four cylindrical grain silos, dug in the tuffeau. Although a local tradition attributes them to Julius Caesar, their construction actually dates back to 1548, under the direction of John Gastignon, perhaps inspired by the plans of the Italian architect Dominique de Cortone. These silos, designed to preserve cereals through a system of upper and lower galleries, have never been mentioned as operational in the historical texts. Their operating principle, based on grain respiration and CO2 emission, was later studied without success by Guillaume Louis Ternaux in the 19th century.

The silos, lined with bricks and separated from the rock by a layer of sand, communicate with each other through galleries and a 22-metre staircase linking the top of the hill to the basement. In 1588, the site was bought by the Order of the Minimes, whose neighbouring convent, founded in 1493, spread between the hillside and the Loire. A corridor was pierced around 1830 to facilitate access to elevators, but no document confirmed their actual use. Their innovative design, taken over in 1737 by Bernard Forest de Belidor in Hydraulic Architecture, nevertheless bears witness to the technical ingenuity of the Renaissance.

The wrong attribution to Julius Caesar probably comes from the confusion with the Châteliers' oppidum, located on the plateau above the attices, and from a fantasy interpretation of a 12th century text evoking "chicken attics". The 19th century research, conducted by Jean-Louis Chalmel and Étienne Cartier, definitively ruled out the Roman hypothesis, confirming their construction in the 16th century. The materials (bricks, tuffeau) and techniques used, similar to those of the "Pears d'Ardres" (1530), built under Charles Quint, reinforce this dating. Ranked historic monuments in 1948, these silos remain a rare testimony to the hydraulic and agricultural architecture of the Renaissance.

Today integrated into the Hotel Le Choiseul, the Greniers de César are partially visited. Their state of conservation, although redesigned (modern bays, straight staircase), makes it possible to appreciate their original design: hemispheric cupolas pierced by holes, central wells, and gravity drain system. Their inscription as historic monuments, five centuries after their construction, underscores their heritage value, mixing ancient legend and technical reality.

Discussions about their actual use (conservation of grains, medicinal plants by Gastignon, or simple unfinished project) persist. The unsuccessful tests of the 19th century and the absence of contemporary written sources leave a mystery on their exact function. Their proximity to the castle of Amboise, a royal residence, and their connection to the influential Renaissance architect Dominique de Cortone make it an emblematic site of architectural innovation of the time.

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