Glen Helen Regional Park, Regional park near Cajon Pass, San Bernardino County, US

Glen Helen Regional Park is a county park beside the Cajon Pass in San Bernardino, California. Its open mowed lawns are dotted with tall evergreens and broad deciduous trees, and a row of trees lines the edge of a body of water. The park holds the Glen Helen Amphitheater, the largest outdoor amphitheater in the United States, and a motocross track.

The area was originally called Sycamore Grove and functioned as a crucial stopping point along the Mohave Trail for Native Americans and early explorers. Over time it transformed into a modern recreation area while retaining its geographical significance.

Sycamore Grove was named by the 1851 Mormon colonists, who camped here from June to September while negotiating the purchase of Rancho San Bernardino. The grove was later called Martin's Ranch, Sycamore Valley Ranch and Glen Helen Ranch. A California Historical Landmark marker, No. 573, stands in the park; it was moved here in 1972 from the original grove, 1 mile away.

The park entrance is at 2555 Devore Road, 0.7 miles west of Devore, where the California Historical Landmark No. 573 marker for Sycamore Grove now stands; the monument was moved into the park in 1972. The motocross track is known for steep hills, jumps and banking, and the park has hosted off-road races since 1985. The swimming complex opened in May 1988.

Glen Helen Amphitheater, opened in July 1993 as the Blockbuster Pavilion, is described in the sources as the largest outdoor amphitheater in the United States. The park around it also holds a motocross track noted for steep hills, jumps and banking, and has hosted off-road races since 1985.