Olompali State Historic Park is a 700-acre (2.8 km2) California State Park in Marin County, California. It consists of the former Rancho Olómpali and was the site of the famed Battle of Olómpali during the Bear Flag Revolt. Rancho Olómpali was purchased by the Californian government in 1977, which turned it into a public park.

Marin County is located in the northwestern part of the San Francisco Bay Area of the U.S. state of California. As of the 2020 census, the population was 262,231. Its county seat and largest city is San Rafael. Marin County is across the Golden Gate Bridge from San Francisco, and is included in the San Francisco–Oakland–Berkeley, CA Metropolitan Statistical Area.