The Cairo Arcology is a massive manmade structure in Cairo only partially visited in Deus Ex: Invisible War. An Arcology (derived from from Architecture and Ecology) is a theoretical superstructure several hundred meters high and multiple square kilometers wide. This structure would be able to comfortably house large buildings and entire environments within itself, and could provide a comfortable home to populations exceeding tens of thousands of people without requiring any outside assistance or expelling any sort of waste. This Arcology was most likely produced with Carbon Nanotubes and Nanoformers, or some other thin yet extremely resilient material, as other building materials are simply not tough or thin enough to build a structure the size of an Arcology.