The top near-town outdoors destination is 375-acre Bartholomew Park, off Castle Rd, where you can picnic beneath giant oaks and hike 2 miles of trails, with hilltop vistas to San Francisco. The Palladian Villa, at the park’s entrance, is a re-creation of Count Haraszthy’s original Pompeian residence. There's also a good winery, independently operated.
Sadly the wildfires of 2017 affected this park and at the time of research it was closed until further notice.