The interior walls, which shone white with a protective layer of whitewash, were made of sun-dried mud bricks. This mixture of clay, sand and straw was placed on stones which isolated them from humidity. Dr Susannah Hagan, Emeritus Professor of Architecture at the University of Westminster and specialist in green architecture, later explained why this building technique is so ingenious: “The secret is in the walls: thick walls of earth or stone that retard the penetration of heat from the sun inside a building during the day and reflect that heat back to the cold sky at night,” she said. cool enough to restart the protection cycle.”

She added: “The skilful use of available building materials [achieves] maximum comfort with minimum resources. In the desert, that means cool without air conditioning and heat without heating.”

As we continued, we passed doors made of simple palm trunks, some studded with brass, as well as low arches, curved alcoves and Dakar – built-in benches – which, perfect for lounging around, usually point to a nearby mosque (there are 21 of them, though only a handful are still in use, and only on Fridays). Sometimes the arches were incised, chiselled, or decorated with delicate paintings (a hand of Fatima, a star, intricate geometries), adding to the mystery and allure.