Mark Byrnes is a former senior associate editor at CityLab who writes about design and architecture.
A look at the best and worst designs from around the world
Each city's subway logo creates a lasting identity not only for the transit system, but for the city - an instantly recognizable icon that represents how we move from place to place. Most are simple (think of the letter 'M' or 'T' placed in a circle or square) but some get pretty complex.
We looked at the logos from nearly every major city's rapid transit system to see which ones worked and which ones really didn't. Here are some of our favorites:
And also, some in need of a serious redesign: