The Groton Town Forest can be reached by heading north on 119. (if coming 
from the Boston area one should go rte 2, north on 495, rte 119 is 2exits 
up).  In the middle of  "downtown" Groton, Main Street stays straight and 
rte. 225 goes left at a fork .  Go left on rte. 225 for maybe .5 miles and 
then rte 225 turns right (there's a big green highway sign), goes downhill, 
crosses the river and shortly thereafter, Town Forest Road will be on the 
left.  The road goes sharply up a short hill.  Take the road until you enter 
the forest.