This five-mile loop is accessible by driving to John Muir Hospital and heading southeast on La Casa Via. You park near the mini-vineyard and walk past an S curve in the road to a home with a gold pineapple atop a column. Pass a fence and follow the sign for the Ridge Top Trail. Suddenly, you're pinwheeling back in time, leaving behind Walnut Creek's Spanish, colonial, and embassy-style glass houses. You jog past oaks and buckeyes, swooping swallows, and tall grasses. The cities and Mount Diablo are visible in the distance. Whenever there's a "V," go left for easier jogging, always remaining on Ridge Top Trail. After more than a mile uphill, descend, cross other paths, and jog by a bench dedicated to a dutiful dog. Climb uphill, then down. Pass under an electrical tower and transfer to the wide Briones-to-Mt.-Diablo trail, going back to your right. Jog through the cow gate. Soon, an elementary school appears, then another trail entrance, but that one misses the mansion-sprawl. You'll remain on the Briones-to-Mt.-Diablo trail all the rest of the way back to where you started. Stay the course, back to the metal fence and the golden pineapple. Dogs invited. Friends check friends for ticks.