Cerro San Luis Obispo, known in Obispeño as łpɨłhɨtšnuka, is a 1,292-foot volcanic mountain rising above San Luis Obispo as one of the Nine Sisters and a defining local landmark. Formed of igneous rock thrust through older Franciscan sedimentary layers, it preserves the core of an ancient volcano. Its steep slopes and encircling trails have made it a major recreation area for hiking, jogging, and mountain biking, including routes to the summit and the Rock Garden descent. The mountain also carries traces of more recent use, including surviving citrus trees planted around 1900 by Civil War veteran G. W. Chandler and ranch land later acquired by Alex Madonna.