Foothills Nature Preserve is a 1,400-acre park and nature preserve in the Santa Cruz Mountains of California, United States, within the city of Palo Alto. From 1969 until 2020, only residents or city employees of Palo Alto and their guests had lawful access to it, a restriction that has sparked "decades-long" controversy and a 2020 ACLU lawsuit. The park was opened to the general public on December 17, 2020.