One of the most interesting mass transit options in San Francisco is the F Line. It seems like the cable cars get all the love, but the street cars that run up and down Market Street and the Embarcadero along the waterfront are pretty interesting themselves. Most of the cars come from cities around the world, and when the cars are from other countries, San Francisco has kept the original signage, so you can get on the Italian car and exit through the "uscita". It is a fun and scenic trip, but these are not just tourist attractions-- the F Line is a very useful way to get around the central and northern sections of The City. By the way, "The City" is the most common nickname for San Francisco here. I was told by everyone before I came not to ever call it "Frisco," but I have yet to hear anyone here say anything about that nickname, or about anything except for "The City."
The F Line:
Another F Line car, this one from Italy, I believe: