What started out more than 30 years ago as a request from the mayor for librarian-led tours of City Hall has evolved into a nonprofit operation with more than 200 volunteers who lead some 50 different walking tours all over San Francisco—entirely for free (though donations are gladly accepted). Guides are local history buffs who live to share their knowledge and wax poetic about their city. Tours cover every niche, nook and cranny of S.F.—from Russian Hill stairways and Alfred Hitchcock film locations to Chinatown tongs and gangs and the 1906 earthquake and fire. Free
Photograph: Courtesy Creative Commons/Flickr/Roger