I have a great appreciation for the Mexico City subway. Handling the 22 million+ population of the wider Mexico City area, I think it is a model for other cities worldwide. Besides being very clean, modern with beautiful polished gold marble floors in most stations, it is inexpensive (only 3 pesos for anywhere in the system, about 25 cents), and has a very clear wayfinding system.

As someone who has difficulty with Spanish (any language other than English actually), I benefit greatly from the pictograms that identify each station. These are consistent throughout the stations and on the trains of each line.

Discussions about the pictograms lead to fascinating stories about the history of the city.

and the pictograms themselves are beautifully designed.