Definition: cellars in tuffeau stone

In fact, discussing underground gastronomy usually means discussing the history of mushrooms or related products, as they require protection from light. The most famous of these is the white button mushroom. Towards the end of the 19th century, many caves and natural cavities in the Ile-de-France region were used exclusively for the cultivation of this mushroom, which has an astonishing yield: 6 hectares (the equivalent of 6 football pitches) in production can yield 180 kg of mushrooms per day! But contrary to its name, most of France's production (70% to be precise) of button mushrooms is harvested in the Saumur region of the Loire, amounting to 500 tonnes per day, thanks to some 1,800 km of cellars dug into the tuffeau stone. It is in this town that you can visit a magnificent mushroom museum, where numerous educational workshops will teach you everything you need to know about cultivated and wild mushrooms. In particular, you will learn about the impressive cycle of mushroom development: grown in large bags filled with compost, the first mushrooms begin to appear after five weeks and can produce up to five harvests in the following two months.
Another famous delicacy is patiently created beneath the earth's surface, again thanks to the intervention of a fungus: Roquefort cheese. Made from sheep's milk (a very terrestrial ingredient!), the cheese is then matured in natural caves in Rouergue, near Saint-Affrique, where the humidity allows the mould to develop properly. It is also a magnificent region, well worth a visit, just a few kilometres from the vineyards of Bergerac.
Cellars dug into tuffeau stone can be found in many regions, for example in the Rhône valley at Château-neuf-sur-Isère, but another region is undoubtedly Champagne. The largest Champagne cellars are in Épernay and Reims. For example, Moët & Chandon's cellars extend for around 28 kilometres of the 110 kilometres of galleries in the Épernay subsoil, particularly around Avenue de Champagne, where a dozen houses have their headquarters. This avenue is classified as a "site of taste". The length of the galleries dug between Reims and Épernay is said to be more than 300 kilometres, which is the length of Switzerland.