Over the Golden Gate Bridge [1] and through the Rainbow Tunnels, to Marin County we go! The Marin Headlands begins at the north side of the Golden Gate and encompass a wide swath of virgin wilderness, former military land [2], and an historic lighthouse [3].
A great place to start your exploration of the Marin Headlands is at the visitors center (Field Rd. and Bunker Rd., 415/331-1540, daily 9:30 a.m.–4:30 p.m.), located in the old chapel on Fort Barry. The rangers here can give you the current lowdown on the best hiking [4] and biking trails [5], beaches [6], and campgrounds [7] in the Headlands.
Links:
[1] http://www.moon.com/destinations/california/san-francisco-and-the-bay-area/sights/marina-and-pacific-heights/golden-gate-bridge
[2] http://www.moon.com/destinations/california/san-francisco-and-the-bay-area/north-bay/marin-headlands/sf-88l-missile-base
[3] http://www.moon.com/destinations/california/san-francisco-and-the-bay-area/north-bay/marin-headlands/point-bonita-lighthouse
[4] http://www.moon.com/destinations/california/san-francisco-and-the-bay-area/north-bay/marin-headlands/hiking
[5] http://www.moon.com/destinations/california/san-francisco-and-the-bay-area/north-bay/marin-headlands/biking
[6] http://www.moon.com/destinations/california/san-francisco-and-the-bay-area/north-bay/marin-headlands/muir-beach
[7] http://www.moon.com/destinations/california/san-francisco-and-the-bay-area/north-bay/marin-headlands/accommodations