Tremont Street Subway / Park Street Station (oldest U.S. subway tunnel)

Park Street Station is the original downtown entrance to the Tremont Street Subway, which opened in 1897 as the first subway tunnel in the United States. The station sits at the edge of Boston Common and has served Green Line streetcars and later light-rail services since opening. The Tremont Street Subway's construction beneath Tremont Street and the Common marked the start of purpose-built underground urban transit in the U.S.