Fes, Morocco's religious and artistic center, features a series of tanneries nearly 1,000 years old that operate in the same manner as when they first began operation. In other words, they use the same concoctions for curing the hides (various mixtures of cow urine, pigeon feces, quicklime, salt, and water) and to clean and soften the tough skins. The workers stomp the skins in the various vats seen in the photo as part of the process. They are part of a guild, in a manner of speaking, and pass down the trade to their sons.