Sutro Project / Conservatory of Flowers
Located just inside Golden Gate Park from the Panhandle, the oldest surviving flower conservatory in the western hemisphere (1878) and consists of 25 tons of glass - and after a 2003 restoration, it seems likely to hold the title for a while longer yet :)
Living inside are more than 2000 plants - some over 100 years old - divided into 5 sections: Aquatic Plants, Highland Tropics, Lowland Tropics, Potted Plants and Special Exhibits. Effectively a large "green house", the conservatory is temperature controlled and can make for a good wet/cold weather day activity.
Watch your fingers in the carnivorous plants section :)
Website: http://www.conservatoryofflowers.org
Wikipedia: http://en.wikipedia.org/wiki/Conservatory_of_Flowers
