Location:
On Sherman Street, off Rindge Avenue

From Route 95/Route 128:

Take Route 2 East toward Cambridge/Arlington, go approx. 5 miles to the end of Route 2
At the end of Route 2, bare right through the light (Alewife T stop should be on your right)
Rindge Avenue is the next left (but no left is allowed) so you actually need to go over the bridge and around the
rotary and circle back to Rindge Avenue where you will now turn right onto Rindge Avenue
Follow Rindge Avenue approx. 1 mile past cemetery on your right
Take a right at the light onto Sherman Street
Continue on Sherman, go over the Railroad tracks, and St. Peters is on your right

From the Storrow drive and Memorial drive intersection:

Take Route 16 toward Arlington
Stay right at the Mt Auburn Street fork.
Cross over Mt Auburn Street continuing on Route 16/Fresh Pond Parkway.
Cross over Brattle, cross over Huron, and continue 1 mile to rotary
Shoot off to the right at the rotary onto Concord Avenue.
Take 3rd light Left onto Walden
Take second light Left onto Sherman
St. Peters Field is on your left

Google Map