Sweeney Ridge is where San Bruno opens suddenly into big Bay Area geography. Trails climb through exposed grassland to views of the Pacific, San Francisco Bay, the airport, and the coastal hills, with weather that can switch from bright to foggy in minutes.
The ridge also carries the Portola discovery-site marker, commemorating the 1769 Spanish expedition's first recorded European sighting of San Francisco Bay. Bring layers and expect wind; the openness is exactly what makes the walk memorable.