and in order to distribute the water across the city directly. In Fes, for example, this was accomplished via a complex network of canals and channels which captured the waters of the Oued Fes (Fes River) and distributed them across the entire city. These water channels (most of them now hidden under buildings) supplied houses, gardens, fountains, and mosques, powered norias (waterwheels), and sustained certain industries such as the tanneries (e.g. the famous Chouara Tannery). Waterwheels were also used to lift water from these canals and into aqueducts to bring them even further, such as the enormous noria, with a diameter of 26 meters, built by the Marinids to supply their Royal Gardens to the north of Fes el-Jdid. Marrakesh, located in a more arid environment, was supplied in large part by a system of khettaras, an ingenious and complex system by which an underground channel was dug beneath the slopes in the surrounding countryside until it reached the level of the phreatic zone. This artificial channel was gently sloped to allow water to drain through it, but was sloped less steeply than the natural terrain so that it eventually emerged at the surface. In this way, the khettaras drew water from underground aquifers located on higher ground and brought them to the surface with the use of gravity alone. Once at the surface, the waters ran along canals and were stored in a cistern or water basin, from which they could then be redistributed across the city. This system was created under the Almoravids (who founded the city) and further developed and maintained by their successors. Oases regions in the desertic areas of Morocco also needed to make extensive use of irrigation and artificial water canals to make agriculture possible. Khettara systems were also used to supplement these water sources, especially as surface waters frequently dried up during the summer months. The Tafilalt oasis region, located along the Ziz River valley, is a notable example of this system. Domestic architecture Riads A riad (sometimes spelled riyad; ) is an interior garden found in many Moroccan mansions and palaces. It is normally rectangular and divided into four parts along its central axes, with a fountain at its middle. Riad gardens probably originated in Persian architecture (where it is also known as chahar bagh) and became a prominent feature in Moorish palaces in Spain (such Madinat al-Zahra, the Aljaferia and the