Fort Mason to Fisherman's Wharf, on my way to the Musée Mécanique.
Take a tip from a local: This is the Inner Harbor, off Jefferson between Jones and Taylor. Come here to catch a 60-90 minute ride on a small fishing boat that goes around Alcatraz Island and just outside the Golden Gate Bridge for a mere $15. Much more fun than the ferry rides that do the same thing for a lot more money down by the piers. The ride outside the GG Bridge is just about the most fun you can have in San Francisco for $15. Expect to get a little wet tho'. You're also putting money in the hands of real fishermen who have had some bad years lately.