Learn about cable cars...
By A Yahoo! Contributor, 8/25/06
2 simple reasons why you must visit this place - it's the only museum of its kind in the world, plus it's free. Great place to learn about the history of the cable cars, and to see the mechanisms that move the cable cars. Simple yet ingenious concept. Set aside about 1-2 hours. Possibly one of the most under-rated attractions in San Francisco.