Big Rock Trail starts on Lucas Valley Road, right near the entrance to Sky Walker Ranch. Yeah, the place where they made some Star Wars movies. The trail gently climbs nearly 1,000 feet to the top of Big Rock Ridge. Great views on the way up and even better views from the top of the ridge. Going down this trail is a total joy. For Marin, this is a 4 star trail. For the rest of the world, it's probably a 3 star, but I like it and gave it 4 stars.