Take Route 3 North to Route 101A West (exit 7 or 8 will work) into Milford. Pick up Route 101 and follow it into Peterborough. Pick up Route 202 North (it's a right off of 101) and take it for about 2 miles then turn right onto Route 136. Follow Route 136 for about 5 miles and Oak Park is on the left just before the entrance to Greenfield State Park.