Sandstone Peak, Mountain summit in Santa Monica Mountains, United States.

Sandstone Peak, also called Mount Allen, is the highest summit in the Santa Monica Mountains at 3,114 feet (949 m). It stands near the western edge of the Santa Monica Mountains National Recreation Area and is made of andesite, a volcanic rock, not sandstone. From the top, visitors see Malibu, the Pacific Ocean, the Conejo Valley and four of the Channel Islands.

The Chumash people lived in and traveled through these mountains for thousands of years before European contact in the 18th century. In the 20th century, the land around the peak passed into public hands and eventually became part of the Santa Monica Mountains National Recreation Area.

The peak's name comes from the Boy Scouts of America, who asked the U.S. Board on Geographic Names to honour W. Herbert Allen, donor of land for nearby Camp Circle X; the board refused because he was still alive. A bust of Allen stands at the summit, and the surrounding land is now the Circle X Ranch unit of the Santa Monica Mountains National Recreation Area.

The trail to the top starts from a trailhead on Yerba Buena Road and follows a loop that passes several rock outcrops before reaching the summit. Starting early in the morning helps avoid the heat, as most of the path has little shade and the sun can be intense in warmer months.

The summit is made of andesite, a volcanic rock, not sandstone. A bust of W. Herbert Allen stands at the top; the Boy Scouts asked to name the peak Mount Allen for him after he donated land for Camp Circle X, but the U.S. Board on Geographic Names refused because he was still living.