The Marin Headlands never ceases to amaze. It's easy to take this historic open space for granted, but go there on a late weekend afternoon and get a refresher on the area's grandeur with a 3.5-mile walk. The route—from Rodeo Beach to Point Bonita and back—doesn't follow a traditional path; it's more about meandering unofficial trails and lightly used roads, and packs in more points of interest than an iPhone app. Starting at Rodeo Beach, walk up the unmarked trail through the ice plant on the southern side of beach, getting great views of the Marin coast. Continue to Battery Mendell and the Bird Island overlook where Northern and Southern views of land and sea are superb. But even better views are found at the radar station. Keep going along the cliff top and watch your footing while spying down toward the sea in search of an old shipwreck (most visible at low tide). Take a short .5-mile (one-way) detour to the Point Bonita Lighthouse (open Saturday to Monday from 12:30 to 3:30 p.m.) Keep the good views coming by passing another old army relic—and one of Marin's best barbecue spots—Battery Wallace—before descending for the last stretch along peaceful Lagoon Trail. Exploratory mission accomplished.
From the Rodeo Beach parking lot, walk south along the beach. Take the unofficial trail up through the ice plant (not the Lagoon Trail—which is what you come back on). Bear right on this trail as it heads up to the Battery Alexander parking lot and the YMCA. Follow the paved road around the YMCA. When you reach the Point Bonita Lighthouse Trail, keep walking along the road to Battery Mendell and the Bird Island overlook. Loop back on the trail behind Battery Mendell (passing two rusted dome structures). The trail continues along the cliff top up to the radar tower. Loop around the tower and take the wide fire road back to the Point Bonita Lighthouse. Make an out-and-back to the lighthouse. Continue on the road to the YMCA. Turn right up the road opposite the YMCA. Pass Battery Wallace. At the next junction follow the signs to San Francisco and the visitor center. At the visitor center take the Lagoon Trail, which starts behind the restrooms. This takes you back to Rodeo Beach. Here's a map of the area, but it does not include the unofficial trails. Rodeo Beach and the Lagoon Trail are dog-friendly, but some of the cliff-top trails might not be safe for dogs.