Directions

From Worcester: 

Take I-290 E and use exits 19/20 on the right to take I-190 N. Get off on exit 6 and turn left on MA-12 N. At the traffic circle, take the first exit to stay on MA-12 N. The 228 in Sterling will be on your left.
 
From Springfield: 
 
Take I-91 N. Take exit 8 for I-291 E/US-20 E toward I-90/Mass.Pike E. Take the I-90 E/I-90 W exit toward Masspike/Boston/Albany. Keep left at the fork, follow signs for Massachusetts Turnpike/Interstate 90 E/Worcester/Boston and merge onto I-90 E/Massachusetts Turnpike. Take exit 10 toward MA-12 N/Auburn/Worcester. Merge onto I-290 E. Use the right 2 lanes to take exit 19-20 for I-190 N to MA-12/Holden/Fitchburg. Take exit 6 for MA-12 N. At the traffic circle, take the 1st exit onto MA-12 N. The 228 in Sterling will be on your left.
 
From Boston:
 
Take I-93 N. Take exit 31 to merge onto MA-16 W/Mystic Valley Pkwy toward Arlington. At the traffic circle, take the 2nd exit onto MA-16 W/Alewife Brook Pkwy. Use the right lane to merge onto MA-2 W via the ramp to Concord. At the traffic circle, take the 4th exit onto MA-111 N/MA-2 W. Take exit 33 to I-190 S/Leominster/Worcester. Take exit 6 for MA-12 N. At the traffic circle, take the 1st exit onto MA-12 N. The 228 in Sterling will be on your left.
 
From New Hampshire:
 
Take I-89 S. Take the exit onto I-93 S toward Manchester/Boston. Keep left at the fork to continue on I-293 S/Everett Turnpike, follow signs for Interstate 293 S/Manchester Airport/Manchester/Nashua. Keep left at the fork to continue on Everett Turnpike, follow signs for Manchester Airport/Merrimack/Milford. Continue onto US-3 S. Use the right 2 lanes to take exit 30A-30B-31for I-495/MA-110 toward Marlboro/Lawrence/Chelmsford. Keep right at the fork to continue on Exit 30B, follow signs for I-495 S/Marlboro and merge onto I-495 S. Take exit 29B to merge onto MA-2 W toward Leominster. Take exit 33 toward I-190 S/Leominster/Worcester.  Take exit 6 for MA-12 N. At the traffic circle, take the 1st exit onto MA-12 N. The 228 in Sterling will be on your left.