The Kairaouine Mosque was the largest complete mosque in Morocco for ages until the recently built Hassan II Mosque in Casablanca. It was founded in the year 857 and then bulked up during the 10th and 12th Centuries so that it currently has sixteen aisles, six fountains, and has a capacity of 20,000 worshippers. The mosque is also highly regarded as one of the oldest universities in the world. It establishes the timings of Ramadan and other significant Islamic festivals.
From the outside maze of the old medina, it is practically impossible for the outsider to gain an overall appreciation of the fine appearance of the Kairaouine Mosque. There are four main entrances to its central courtyard. Non-Muslims are not allowed to enter the interiors of the mosque, although it is possible for the determined traveler to get a peek or two through the openings for a glance at the courtyard. The layout is influenced by the design of the Great Mosque of Cordoba, Spain. The central open courtyard features a large fountain at its central point. The interiors feature fine craftsmanship that has produced domes, arches, wood screens, brass lamps, and richly delineated calligraphy and patterns.
The excellent library holds one of the oldest manuscripts of the Koran in North Africa. Not far from the Kairaouine Mosque is the Medersa el-Attarine, a Merenid school with fine mosaics and details.