Next to the Cliff House, a small wooden building houses a walk-in camera obscura -- an optical device that uses a rotating mirror and lens to project a live, full-colour, 360-degree image of the surrounding coastline onto a parabolic dish in a darkened room. The technology dates back centuries, but watching the waves, rocks, and passing ships appear as a luminous moving painting on the dish never gets old.
A visit takes about fifteen minutes and costs a few dollars. Combine it with a walk along the Sutro Baths ruins and the Land's End trail.