Many museums/zoos offer free admission on certain days of the month. If there are any you know of that are not listed here, please leave a comment below so I can add it.
1st Tuesday
- De Young Museum in San Francisco, CA
- Legion of Honor in San Francisco, CA
- San Francisco Museum of Modern Art in San Francisco, CA
1st Wednesday
- Bay Area Discovery Museum in Sausalito, CA
- Exploratorium in San Francisco, CA
- San Francisco Zoo in San Francisco, CA (SF residents only)
1st Sunday
- CuriOdyssey (fka Coyote Point Museum) in San Mateo, CA
- Oakland Museum of California in Oakland, CA
- Asian Art Museum in San Francisco, CA
2nd Tuesday
- San Francisco Botanical Garden in San Francisco, CA
2nd Sunday
- The Tech Museum in San Jose, CA (Excludes Apr & Aug ’11)
3rd Wednesday
- California Academy of Sciences in San Francisco, CA
If you have a Bank of America debit or credit card, you can get free entry into more than 125 museums nationwide with their Museums On Us program. I counted 11 in Northern California alone, such as Chabot Space & Science Center in Oakland, CA and Zeum in San Francisco, CA.
Those all sound like so much fun and how wonderful that they are all free on those days!