Fez: the medina with a guide, and the tanneries from the terrace

Fez el-Bali is the largest car-free urban area in the world, and even locals get lost; one half-day with a licensed guide (badge, booked through your riad or the tourist office) teaches you the main arteries and saves hours. The Chouara tanneries are viewed from the leather shops' terraces: take the sprig of mint, look, and buy only if you want to. The Bou Inania and Al-Attarine madrasas are the two buildings you shouldn't miss.