Founded in 1062 by the Almouravid Sultan Yousef ibn Tachfin, Marrakech became one ?of the Islamic world's most important artistic and cultural centers. Using much of the wealth plundered during the Almoravid conquest of Spain, Yousef extended and beautified the city. The city's golden age, however, was under Yousef's son Ali, who was born to s Christian slave mother. Besides building mosques, baths and other places, Ali commissioned construction of the expansive Khetara (underground irrigation canal), which still supplies Marrakech’s gardens with water from the High Atlas. This city contains many important monuments, such as AlKoutoubia. Amnara, Saadi Palace, Majorelle gardens, and Palmerais. The focal point of Marrakech is the huge square Djemma el Fna in the medina, and it is the backdrop for one of the world's greatest spectacles.