For flingers who are spending a longer time in SF, a visit to Alcatraz might be of interest.
As of 2003, the gardens on the island are overseen by the Garden Conservancy, The Golden Gate Parks Conservancy, and the National Park Service.
Tours and garden visits are available. The entry fee is the cost of the ferry to the island. Tickets are best purchased in advance, as tours regularly sell out.
Book ferry passage here.
Read about the history of the gardens, and about tours and planning a visit here.
And don’t forget to leave room in your luggage for a t shirt.