Tremont Street Subway served stations for 50 years.
  The landmark designation encompasses the still-extant portions of the early tunnel, roughly from Court Street to Charles Street, and includes the original Classical Revival head houses of the Park and Boylston stations which are still in use
The western Public Garden portal was replaced in 1914 with two portals, one in the middle of Boylston Street adjacent to the old portal, and the other at the west end of the Boylston Street subway, just east of Kenmore Square

