Agadez, formerly spelled Agadès, is the fifth largest city in Niger, with a population of 110,497 based on the 2012 census. The capital of the eponymous Agadez Region, the city lies in the Sahara desert, and is also the capital of Aïr, one of the traditional Tuareg–Berber federations. The historic centre of the town has been designated a World Heritage Site by UNESCO.