Science has rarely been as much fun as at the new facility of this venerable museum designed by Renzo Piano, the Italian master of technologically sophisticated architecture. Set in the spacious Golden Gate Park (next to the de Young Museum by Herzog & de Meuron) in San Francisco, this building is itself eco-friendly its &lsquogreen roof&rsquo realises Piano&rsquos concept of lifting a bit of the park and sliding the building in under. Inside, the tropical rainforest in a 90ft diameter glass dome is a scene-stealer. You walk up its ramp curling around trees, birds, insects and butterflies to reach the elevator that takes you down below the water. A special moment is the glass tunnel that gives you a few glimpses of aquatic life from under. There is also the spectacular planetarium and the reinstalled natural history gallery. Don&rsquot miss the feeding of the African penguins &mdash your reward will be a memorable smile of wonder-struck excitement on your child&rsquos face. See www.calacademy.org.