San Francisco, California, USA
The Barbary Coast Trail is a 3.8 mile walking tour of San Francisco. The trail is a pretty decent attempt to cover the sites (I say you can skip the old mint!). It will take about a day to complete and you probably don't want to have little kids try it.
Plaques in the sidewalk show you the way (ignore the cigarette). Guides and audio are available from the Barbary Coast Trail site. However, I suggest you just print out the trail map, and walk it yourself. Do not attempt to walk the cable car sections of the trail unless you are in really good shape and want to put that belief to the test.