A couple of nice boulders and a chossy quarried cliff with some pitons in it. One boulder along the trailside is quite beautiful, with a large ~14' overhanging prow. The rock quality is decent granite (read: mostly choss, some quality lines).
Be cautious of the summer camp just south of the boulders.
A few hundred yards north of the Mason Rd / Rt 13 intersection in Brookline, NH, park on the left side of the road just past the summer camp. There is a small 4x4 trail that leads east into the woods. Follow this to the fire road then walk the fire road to most of the boulders. The first/best boulder is below the trail about 5 minutes into the woods. More rock is out there (quarried cliff, a few other boulders), but I don't recall them being all that great.