Directions

From Worcester: 

Take I-290 E and use exits 22/23 on the right to take I-190 N. Get off on exit 14 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 6 for I-291 E/US-20 E toward I-90/Mass. Pike E/Boston. Keep left, and follow signs for I-291 E. Continue onto I-291 E/US-20 E. Continue to follow I-291 E. Take exit 7 to merge onto I-90 E/Massachusetts Turnpike toward Boston. Take exit 90 to merge onto I-290 E toward Worcester. Use the right 2 lanes to take exit 22-23 for I-190 N toward MA-12/Holden/Fitchburg. Continue onto I-190 N. Take exit 14 for MA-12 toward Sterling/Clinton. The 228 in Sterling will be on your left.
 
From Boston:
 
Take exit 28B to merge onto I-95 S toward Waltham. Use the right 2 lanes to take exit 50A-50B for US-3 N/Middlesex Turnpike toward Lowell/Burlington. Keep left to continue toward US-3 N. Keep right at the fork to continue on Exit 50A, and follow signs for I-95 S/US-3 N/Lowell. Continue onto US-3 N. Use the right 2 lanes to take exit 81B-C to merge onto I-495 S toward Marlboro. Take exit 78B to merge onto MA-2 W toward Leominster. Take exit 101 to I-190 S/Leominster/Worcester. Take exit 14 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, and follow signs for Manchester Airport/Merrimack/Milford. Continue onto US-3 S. Use the right 2 lanes to take exit 81A-81B-81C for I-495/MA-110 toward Marlboro/Lawrence/Chelmsford. Keep right at the fork to continue on Exit 81B, follow signs for I-495 S/Marlboro, and merge onto I-495 S. Take exit 78B to merge onto MA-2 W toward Leominster. Take exit 101 toward I-190 S/Leominster/Worcester.  Take exit 14 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.