premise: Tremont Street Subway served Boylston station.
hypothesis: Tremont Street Subway . It now forms the central part of the Green Line , connecting Boylston Street to Park Street and Government Center stations . The tunnel originally served five closely spaced stations : Boylston , Park Street , Scollay Square , Adams Square , and Haymarket , with branches to the Public Garden Portal and Pleasant Street Incline south of Boylston .