Acton, Massachusetts

MBTA - Fort Pond Brook Bridge (MP 25.03) (Middlesex County, Massachusetts)
Built 1845
Stone arch bridge over Fort Pond Brook on MBTA Fitchburg Line
Open to traffic

MBTA - Fort Pond Brook Bridge (MP 26.26) (Middlesex County, Massachusetts)
Built 1844, widened on two subsequent occasions
Stone arch bridge over Fort Pond Brook on MBTA Fitchburg Line
Open to traffic

NH - Nashoba Brook Bridge (Middlesex County, Massachusetts)
Built ca. 1907
Deck plate girder bridge over Nashoba Brook on NH Framingham & Lowell Line
Derelict/abandoned