Public transit in Boston, the MBTA, has a regional system of commuter rail lines, one of which goes right to Concord from Boston's North Station. It's the Acton/Fitchburg line. When you get off the train, you'll find places to eat and get a cup of coffee right across the street. Walk a few blocks farther toward the town center, and you'll find quaint shops, historical markers and sites, and more places to eat.