Harwood Train Yard
There is very little known history of the Harwood Train Yard. All that's known is that the yard was part of a railroad line connecting Harwood and Portland View to Portland Harbor via a tunnel underneath the district of Saint Mark's. it is unknown when exactly the line was abandoned, but the line appears as though it has not been used in over 50 years, at the most.
The yard still exists as of events in GTA Liberty City Stories (1998) and GTA III (2001), with track and a few old rusting flatcars. The tunnel is still there, but most of the rails have been removed in it (only a tiny section goes into the tunnel before it ends abruptly). The player is able to enter the tunnel by driving around the old loading freight platforms and onto the tracks, then turning west into the tunnel, which exits behind Supa Save!/Fidl in Portland Harbor.