The Bay Area Rapid Transit
I have traveled on BART a million times and I have literally lost count the different stations I have gone in and out of. While many don't really have any artistic aspect to them, there are some that do. There's not a lot, but there is something worth seeing.
An etched image of Tallie Maule, architect, inside the Embarcadero station
While there are still some stations in different parts of the world which sell tickets from ticket booths, there is none of that in BART. Tickets are dispensed by machines like this.
Get a load of this bike storage.
Here's another one.