Tremont Street subway

Tremont Street subway
A flying junction on the now-abandoned southern branch of the Tremont Street subway, south of Boylston station, approaching the Pleasant Street incline (1898 photo)
LocationBoston, Massachusetts
Coordinates42°21′23″N 71°3′47″W / 42.35639°N 71.06306°W / 42.35639; -71.06306
Built1897
ArchitectHoward A. Carson
Architectural styleClassical Revival
NRHP reference No.66000788
Significant dates
Added to NRHPOctober 15, 1966 (1966-10-15)
Designated NHLJanuary 29, 1964 (1964-01-29)

The Tremont Street subway in Boston's MBTA subway system is the oldest subway tunnel in North America and the third-oldest still in use worldwide to exclusively use electric traction (after the City and South London Railway in 1890, and the Budapest Metro's Line 1 in 1896), opening on September 1, 1897. It was originally built, under the supervision of Howard A. Carson as chief engineer, to get streetcar lines off the traffic-clogged streets, instead of as a true rapid transit line. It now forms the central part of the Green Line, connecting Boylston Street to Park Street and Government Center stations.