First U.S. subway (Tremont Street Subway)

The Tremont Street Subway opened on September 1, 1897, and is widely documented as the first subway tunnel constructed in the United States. Its original Park Street station and platforms were built beneath Park Street adjacent to Park Street Church. The tunnel initially carried electric streetcars and later became part of the MBTA Green Line. Park Street Church (the surface landmark) stands above the site of the original station.