Briones Regional Park is a 6,000-acre open space by Lafayette and Pleasant Hill. The area was originally part of a land grant made to the widow of Filipe Briones in 1842; it was then established as a regional park in 1967. The park includes grazing land, a research center for University of California, Berkeley, and a 1,483-foot peak.
Though there are scores of hiking trails throughout Briones, the Buckeye Ranch area tends to be less traveled, and it offers wildflower-covered hills and beautiful, 360-degree views. Parking is at the trailhead, and once you are through the gate, keep right on the fire road. You will meander through dense woods for a about a mile before you cross a small stream and head uphill. This trail dissipates eventually, and you will find yourself turning right up a steep hill. Continue straight up the hill, and at the top you will hit a perpendicular fire road. Take a break here to appreciate the huge views, then turn left and follow the road through the bluffs.
This route will bring you on a round trip along the ridge. Keep turning left whenever you are faced with a junction. After a few miles you will descend back down to the trail you left in the gully. Follow this trail back your car.
Note that this adventure requires a small section of off-trail hill climbing; be sure to travel with a map of the area.