Essentials: Mexico City

1) Mexico City has launched the Hoy No Circula program to improve air quality in the city. As a result, only cars with certain numbers on their license plates are allowed to drive on particular days. Do the city's residents adhere to this rule? Sure, but by owning multiple license plates.

2) The fact that Mexico City needs the Hoy No Circula program becomes clear when you consider the number of taxis – over 140,000! 

3) There is only one royal castle in North America, and it is located in Mexico City. The 67-meter-high Chapultepec Castle was built by the Spanish in 1785.

4) Mexico City is the proud home of four World Heritage Sites: the historic center and borough of Xochimilco with its famous canals, the former home and studio of architect Luis Barragán, and UNAM, one of the oldest and largest universities on the continent. 

5) Thirty to forty centimeters! That's how much Mexico City sinks every year. This is due to the muddy ground on which the city stands, as it was built on a dried-up lake. And underneath that is groundwater, which is pumped out and erodes the soil. Mexico City will therefore continue to sink.