The Legion of Honor, San Francisco's most beautiful museum, displays an impressive collection of 4,000 years of ancient and European art in an unforgettable setting overlooking the Golden Gate Bridge.
http://legionofhonor.famsf.org/
This was a great drop in spot but it looks bigger form the outside than the exhibits actually are
Make sure to be very careful about what you photograph in the museum. Some areas you are allowed to and others you are not, but the signs are not always very visible- and the staff will yell.