The California Academy of Sciences is a research institute and natural history museum in San Francisco, California, that is among the largest museums of natural history in the world, housing over 46 million specimens. The Academy began in 1853 as a learned society and still carries out a large amount of original research. It is California's oldest museum.
Completely rebuilt in 2008, the building covers 400,000 square feet (37,000 square metres). The primary building in Golden Gate Park reopened on September 27, 2008.