Website says it has 35 miles of fire roads and trails. Has just about everything - some great singletrack, roots, rocks, technical stuff, doubletrack, singletrack, enough hills to make for some good climbs. Real fun place overall, lots of trails to explore.
FROM BOSTON: Take 93 North to exit 41, follow 125 north (toward Andover), for about 4 miles to the State Police Barracks (on right). Turn right on Harold Parker Rd to Jenkins Rd. Turn left on Jenkins Rd, right onto Salem Rd, Headquarters is Approx 1-1 ½ miles on the left.
http://www.singletracks.com/item.php?c=1&i=2567