An alternative to traditional cities

Large-scale arcologies 

are emerging as an alternative to traditional cities

By the 22nd century, these towers have evolved into some of the mightiest structures ever built: of such immense volume that some cover several kilometres in girth, typically rise over 1.5 kilometres in height* and accommodate millions of people.** Some are partially or fully merged into mountainsides and other landscapes – resembling enormous ant colonies, and living up to their portmanteau of "architecture" and "ecology". This scale of engineering has been made possible through advances in materials science, with carbon nanotubes utilised to cope with the massive forces involved. The sheer size and strength of arcologies makes them virtually immune to earthquakes, hurricanes and other disasters.