Abuja's geography is defined by Aso Rock, a 400-metre monolith left by water erosion. The Presidential Complex, National Assembly, Supreme Court and much of the town extend to the south of the rock. "Aso" means "victorious" in the language of the (now displaced) Asokoro ("the people of victory").
Other sights include the Nigerian National Mosque and the Nigerian National Christian Centre. The city is served by the Nnamdi Azikiwe International Airport, while Zuma Rock lies nearby. Abuja is known for being the best purpose-built city in Africa as well as being one of the wealthiest and most expensive; however, the population on the semi-developed edges of the city are living in shanty towns such as Karu. Karu, originally planned to house the capital's civil servants and lower income families, still has no running water, sanitation or electricity.
