Bread in Pompeii was produced daily in local bakeries. The Bakery (pistrinum) of Popidius Priscus contains four large millstones made from porous lava, traces of a stable, four storage rooms and a large oven which was used for baking the bread. This bakery had no adjoining shop, so the bread was probably sold on to other shops or to street vendors, called libani.
World History Encyclopedia
The Pistrinum on Vicolo Storto belonged to N. Popidius Priscus and is a fine example of a bakery in which the whole cycle of breadmaking from milling to baking the bread was performed. After baking, the bread, which came in several different varieties, was then generally sold on in an adjoining shop, although this was not always necessarily so. In this establishment the equipment for the production of bread consisted of four millstones made from porous lava, a very hard wearing stone that wouldn’t lose fragments and spoil the flour produced.
AD 79: Destruction and Rediscovery