Point Bonita Lighthouse (415/331-1540, www.nps.gov/goga/pobo.htm [1], Sat.–Mon. 12:30 p.m.–3:30 p.m.) has been protecting the Headlands [2] for over 150 years. It remains an active light station to this day. You need some dedication to visit Point Bonita, since it’s only open a few days each week and there’s no direct access by car.
A half-mile trail with steep sections leads from the trailhead on Field Road. Along the way, you’ll pass through a handmade tunnel chiseled from the hard rock by the original builders of the lighthouse, then over the bridge that leads to the building proper.
Point Bonita was the third lighthouse built on the West Coast and is now the last manned lighthouse in California. Today, the squat hexagonal building shelters automatic lights, horns, and signals. For a special treat, call the lighthouse to book a spot on a romantic full-moon tour.
Links:
[1] http://www.nps.gov/goga/pobo.htm
[2] http://www.moon.com/destinations/california/san-francisco-and-the-bay-area/north-bay/marin-headlands