are mandatory for many protected varieties, but industrial cheese is often made in stainless steel, especially in North America, where the use of copper is outlawed. This has been suggested as one factor in the failure of North American cheeses to achieve the levels of flavour of the Alpine originals. In some places specific old copper vats can be "grandfathered" in. History According to the Historia Augusta, the Roman emperor Antoninus Pius fell ill and died in 161 after eating a large quantity of "Alpine cheese" ("cum Alpinum caseum in cena edisset avidius") at Lorium, near Rome. What the character of this cheese was is impossible to say, but it was evidently capable of being transported several hundred miles. There is evidence that in the Middle Ages Alpine cheesemaking was encouraged by local monasteries who owned large tracts of little-used Alpine land, and took cheese as tithes, in effect rent. One of the largest was the Abbey of Saint Gall in Switzerland, which owned much of the Appenzell region from the 10th century on. Muri Abbey was founded in 1027 with a large donation of Alpine wilderness, which it settled by offering a starter pack of equipment and animals to peasant families. Cheesemaking soon became an important part of the new local economy, with the tithe cheeses delivered to the abbey each Feast of Saint Andrew, on 30 November. Typically, about a dozen households combined their herds for the summer season, appointing a head cowman, and constructing high chalets to make cheese in. The very hard Italian "grana" cheeses are regarded as a related group; the best known are Parmesan and Grana Padano. Although their origins lie in the flat and (originally) swampy Po Valley, they share the broad Alpine cheesemaking process, and began after local monasteries initiated drainage programmes from the 11th century onwards. These were Benedictine and Cistercian monasteries, both with sister-houses benefiting from Alpine cheesemaking. They seem to have borrowed their techniques from them, but produced very different cheeses, using much more salt, and less heating, which suited the local availability of materials. The Black Death in the mid-14th century hit the Alps hard, and promoted an increase in grazing with cows rather than sheep or goats. The Protestant Reformation, which swept Switzerland if not other Alpine regions, removed the monastic landlords, and also some restrictions on eating cheese during Lent (although these already did not apply