Bald Hill Reservation features 10 miles of hiking trails near Boxford, MA.
Take 95 North to exit 51 (Endicott Road) and bear left at the end of the exit ramp. You'll see Middleton Road on your right very shortly - go down there about a mile and a half and you'll see the entrance on your left. It's a small entrance with a fire gate, a no parking sign, and a small message board. Just park off to the sides to avoid a ticket or towing.
http://www.tripleblaze.com/trail.php?c=3&i=460