A few months ago, I walked with a meetup group through San Francisco and encountered a number of "hidden" staircases. Well, they weren't actually hidden if you knew where to look for them.
The picture here is of the "Farnsworth Steps" on Farnsworth Lane. It was named after Philo Farnsworth who was one of the first inventors of the television back in the late 1920's. Mr. Farnsworth used to live at the end of this stairway.
You have your choice of walking off your food at a number of San Francisco stairways listed here on the sisterbetty.org website.