Sandstone Peak is the highest point in the Santa Monica Mountains at an elevation of 3,111 feet. It is beautiful, with sweeping views out to the Pacific Ocean and Channel Islands and inland to the Conejo/Simi Valleys.
From the Conejo Valley, take Westlake Boulevard south until it becomes Decker Canyon, make a right on Mulholland, then right on Little Sycamore Road, which becomes Yerba Buena Road, with an endpoint of Sandstone Peak Trailhead. The trailhead is just west of Circle X Ranch, 12896 Yerba Buena Road, Malibu, which formerly was a Boy Scout camp.
The hike is only about 3 miles round trip. Depending on how fast you go, the 1.5 mile climb to the top can take anywhere from 25 minutes to an hour. The trail is well maintained but has quite a bit of loose stones, so be sure to wear good shoes so you don't twist an ankle. The starting elevation at the Sandstone Peak trailhead is 2,030 feet, so you'll be climbing over 1,000 vertical feet over 1.5 miles.
Visit the National Park Service website at www.nps.gov/samo/planyourvisit/circlexranch.htm for more information about the Circle X Ranch area and a printable pdf map of the trails that will get you to Sandstone Peak, including the Mishe Mokwa Trail, Grotto Trail and the Backbone Trail.
To extend the hike, check out Sandstone Peak to Inspiration Point and Tri Peaks.
There are several ways of getting to Sandstone Peak. The most direct way is the trailhead directly up to Sandstone Peak (takes about an hour) and the other is via the Mishe Mokwa Trail, which takes you to Split Rock, through a loop that connects you to the Backbone Trail to Sandstone Peak. This trail will give you views of "Balanced Rock" that you'll see pictured below. Once you reach Sandstone, you'll find a steep staircase that will take you to the peak.