Originally Posted by tom tulpe

Where outside NYC are those stations? Most "underground" stations are just the old stations at ground level with construction on top of them (Los Angeles Union Station, Chicago Union Station).

In Europe the only major mainline stations I can think of where mainline trains use underground platforms are Antwerp Central, Brussels Central, half of Berlin Hauptbahnhof (north-south tracks, east-west tracks are elevated), Barcelona Sants, and tracks 31-34 of Zurich Hauptbahnhof. Lots of commuter train lines are underground though, as are many mainline airport stations (Zurich, Geneva, Charles de Gaulle Airport TGV, Frankfurt, Schiphol airport).