Moroccan invasion of 1591. The town remained small until French rule was imposed in the early twentieth century, when the port was expanded. It had a population of 57,978 in 2005.
Other attractions in Gao include the original fourteenth-century Gao Mosque, a museum devoted to the Sahel, markets including a night market, and La Dune Rose, a sand dune named for its appearance at dawn and nightfall.
Gao has an international airport and is linked to other cities along the Niger River, including Timbuktu, by a ferry service. In 2006 a new bridge across the Niger at Gao was inaugurated. While for centuries a transit and trade hub, the tourist industry, especially serving cruises of the Niger, has also become important to the local economy.
Mud either as brick or as pisé is associated with the greatest examples of West Africa's monumental architecture. The area most suited to mud-brick architecture is the savanna, where there is enough water to make bricks, plaster, and pisé (rammed earth) yet not too much rain to dissolve the dried mud walls. Traditionally, rammed earth buildings are common in arid regions where wood is in scarce supply. The traditional methods of mud architecture vary from one town to another; in Djenne cylindrical mud bricks were used, whereas in other towns simple dried-earth lumps were the building material.
Mud architecture lends itself to the creation of plastic sculptural forms on fairly simple structures, thus a simple rectangular facade can be enlivened by the addition of crenellations, engaged pillars, and decorative panels.
The Tomb of Askia is the central commanding feature of the Great Mosque of Gao. This layout pays homage to the Saharan tradition of prominent ancestral tumuli or tomb mounds erected over graves that date to before 1000 B.C.E. This large feature was incorporated into a new mosque building tradition in which the mosque itself becomes a combination of tomb, minaret, and sacred enclosure.
The tomb itself is built on an almost square plan measuring about 14 by 18 meters. The four faces are aligned according to the cardinal directions, as are the outer walls of the mosque. The earthen tomb rises from its base as a stepped pyramidal tower articulated by three distinct levels to a height of just over 10 meters. The earthen exterior walls taper inward upon ascent and are distinguished by many protruding toron, or stakes, of acacia wood. Such stakes bristling from the walls provide a permanent scaffolding for replastering the mud that has washed away. When contrasted with other mosques displaying the more common straight and linear toron, such as at the Djenné Great Mosque, these stakes give the Tomb of Askia a wild appearance. The tomb is enclosed within the eight-foot wall of the larger mosque complex, the area of which is about 45 by 50 meters.
The tomb is a radical departure from the prior conical articulation of the popular Songhai earthen tumulus. Furthermore, surmising based on the numerology of its unique shape, Labelle Prussin claims that the mathematical articulation of the three-level, four-sided pyramid corresponded to "the traditional ancestors (who) were enveloped in the robes of Islam and magic squares." However, this style was probably borrowed from the square, three-stepped stairway minarets of the Ibadite zawiyas, or holy shrines, of the Mzab region of southern Algeria, a cultural adaptation that is made understandable by the fact that Askia Mohammed hosted numerous Ibadi scholars. Further, it must be noted that a similar building evolution was happening contemporary to Askia's reign under the Fulani in the Hausa region of northern Nigeria, such as with the Great Mosque of Kano.
Relatively recent modifications to the site have included the expansion of the mosque buildings in the 1960s and mid-1970s, and the 1999 construction of a wall around the site. It has also been regularly replastered throughout its history, a process essential to the maintenance and repair of mud structures. Electricity was added in the early 2000s, allowing for ceiling fans, lights, and a loudspea