Sprawling across a high plateau framed by mountains and volcanoes, Mexico City has expanded tenfold in both population and area since 1940. With a population of 18 million plus, the city region generates nearly a quarter of Mexico’s wealth, attracting people – many of them young – from the rest of the country to the Aztecs’ original ‘floating city’.

The region faces a major challenge in co-ordinating services and infrastructure across the administrative boundaries of the two separate governing entities that make up Mexico City’s wider metropolitan area – the Federal District and the State of Mexico. Its central tree-lined boulevards and security-guarded shops and offices contrast with the continuous spread of informal housing that clings to the steep hills and extends outwards to the horizon.

The income gap between rich and poor remains wide, and a high crime rate dominates, with security a prime concern alongside pollution and traffic congestion, exacerbated by car-oriented policy and investment, in a city where petrol is cheaper than bottled water. Fear has motivated the presence of security forces and the construction of gated residential and commercial compounds across the city.

The new city mayor is now pushing for more coordinated governance to control sprawl, revitalising its historic centre, introducing more sustainable transport, and starting to tackle its acute water shortage and the crumbling urban fabric that reflects decades of unstructured growth and poor resource management.