The Bay Model was built in 1957 and used by the Army Corps of Engineers to study the effects of interventions like dredging shipping channels and accidents such as oil spills. Though retired as a research tool in 2000 (presumably the Corps now uses computer models), the model continues to operate as a public education center.
The Bay Model Visitors Center is located in Sausalito at 2100 Bridgeway, and is open Tuesday through Saturday in winter and on Sundays as well in the summer. But this Saturday from 11:00 to noon, there is a special walking tour of the model entitled "Back in Time on the Bay", which explores changes (both natural and unnatural) to the Bay from pre-historic times to the present. If you (like me) can't make it this Saturday, the tour will be offered again on Saturday 21 February.