A Beaux-Arts railroad terminal in New York City. There are 44 platforms (no other railway terminal in the world has this many) and 67 tracks.
The place is full of surprises. Not only is there a whispering gallery (where your whisper can be heard elsewhere in the gallery) but there is also a top-secret M42 room (which does not appear on any map of the place or even on its blueprint) hidden somewhere, and a tennis court.
There are many shops and places to get food located inside the Grand Central Terminal. You can get there easily by subway (Lines 4, 5, 6, 7 and S) or by bus (Lines M1, M2, M3, M4, M5, M42, M98, M101, M102, M104, Q32).