The park's archaeological significance is not immediately obvious to weekend picnickers. Shell mounds -- accumulations of discarded shells, bone, and soil built up over centuries of occupation -- mark the presence of indigenous communities who harvested the coast's marine resources. Stanford University professor Patrick Hunt conducts regular excavations at the site, each season revealing more about the lifeways of the people who inhabited these hills. The shell mounds are fragile records, easily disturbed by foot traffic or construction, and their preservation within a public park represents an unusual intersection of recreation and research.

After the original indigenous inhabitants, the land passed through the familiar California sequence of Spanish mission, Mexican rancho, and American subdivision. Following the death of the rancho-era landholder, the property was broken into smaller parcels and a wagon trail was cut from San Bruno station to the San Andreas Valley, later paved into Crystal Springs Road. By the mid-twentieth century, San Mateo County recognized the hills' recreational value. Parks Director Ralph Shaw led the effort to establish the park, initially called North County Park, which was dedicated on May 22, 1960. A Master Plan published in 1981 formalized the park's dual role as a community recreation space and a site of historical importance.

Junipero Serra County Park occupies a hilly tract between Interstate 280 and El Camino Real, east of the Crystal Springs watershed and west of the bayside suburbs. El Zanjon Creek flows along the park's north and west sides before joining San Bruno Creek. The terrain is steep enough to feel wild but accessible enough for families; paved roads lead to picnic areas and a youth camp, while City Park Trail connects eastward to San Bruno City Park and a southern entrance opens at the end of Helen Drive. From certain vantage points in the park, you can see both the bay and the wooded ridgeline of the Santa Cruz Mountains. The view is a reminder that the peninsula is narrow -- that ocean and bay are never far apart, and that this green space survives because someone in 1960 thought the hills were worth more than what could be built on them.