The Newark City Subway was built between 1929-1937 and was originally used as an off-street route for some of the Public Service trolley lines. The underground portion is only a mile long, and parts of it have been closed off since the streetcar lines were discontinued in 1952. Until a few years ago, urban explorers resourceful enough to find a way in could still see the old trolleys that were stored in these areas, but they’ve since been donated to museums and other cities.
Via: weburbanist.com
Subways, undergrounds and metro maps 