There is a compulsive fascination about the tanneries Chouwara, the biggest in Fez and the most striking sight in the Medina. Every morning, when the tanneries are at their most active, cascades of water pour through holes that were once the windows of houses, hundreds of skins lie spread out on the rooftops to dry, while amid the vats of dye and pigeon dung (the white vats at the back), an unbelievably Gothic fantasy is enacted as tanners treat the hides. The rotation of colours in the honeycombed vats follows a traditional sequence – yellow (supposedly “saffron”, in fact turmeric), red (poppy), blue (indigo), green (mint) and black (antimony) – although vegetable dyes have largely been replaced by chemicals, to the detriment of workers’ health.

This “innovation” and the occasional rinsing machine aside, there can have been little change here since the sixteenth century, when Fez replaced Córdoba as the pre-eminent city of leather production. As befits such an ancient system, the ownership is also intricately feudal: the foremen run a hereditary guild and the workers pass down their specific jobs from generation to generation.

For all the stench and voyeurism involved, there is a kind of sensuous beauty about the tanneries. However, it is a guilty pleasure, as one glance across at the gallery of camera-touting foreigners snapping away will testify.