Alum Rock Park, Urban park in Alum Rock district, San Jose, US

Alum Rock Park covers 720 acres (290 hectares) and contains oak woodlands, grasslands, and creek corridors with 13 miles (21 kilometers) of pathways winding through changing terrain. The routes pass through shaded canyons and open hillsides where views of the Santa Clara Valley appear between the trees.

The city established the grounds in 1872 as a public retreat after a health resort drawing visitors from across the valley opened around mineral springs. A narrow-gauge railway connected the canyon to downtown San Jose from 1890, carrying guests to the bathhouses and picnic areas.

Indigenous communities called the stream Shistuk, while Spanish colonists named it Aguague, marking the layers of settlement in this valley. Hikers today follow the same watercourse paths once traveled by native groups gathering acorns and medicinal plants.

Visitors find picnic sites with grills, playgrounds, and restrooms at several points along the main road through the park. Early morning or late afternoon offers cooler conditions for hiking, especially during summer months.

White deposits near the entrance were misidentified as alum when they are actually different minerals, but the name stuck anyway. The spring that once drew bathers still flows at the same spot, though the bathhouses disappeared long ago.