A few months ago, my girlfriend and I decided to ride our horses on a longer trail ride. We started at the Purissima Creek Open Space preserve . We started at Purisma Creek Road parking lot and rode along Purisma Creek trail until we reached Skyline Drive. There we crossed the road into Huddart Park and Rode on Skyline trail until we reached the access point to Corte Madera.
By that time we felt we had gone far enough and turned back. On the way back we stopped at the Methuselah tree which one of the few Old Growth redwoods left in the Bay Area. At over 2000 years old is is an enormous tree and stands beautifully strong. It is little known but not difficult to access. For us, it was a 20 mile ride. But totally worth it.