The "whispering gallery" is located on the Grand Central Terminal dining concourse near the famous Oyster Bar & Restaurant. Here, the acoustics of the low ceramic arches can cause a whisper to sound like a shout. To test it out, you and a friend will have to stand in opposite corners of the large arched entryway. Now face the corner and whisper. Your friend should be able to hear your voice as if you were right next to them, not whispering into a far-away corner.
According to experts, this happens because the whisperer’s voice follows the curve of the domed ceiling. The Whispering Gallery is a popular spot for marriage proposals.
More into the depths of Grand Central:
Built in the 1890s, Grand Central is widely hailed as one of the city's great interiors. The building through which nearly 150,000 commuters still pass each day, however, is only a part of the structure. Underground there are two levels of tracks that spread into a vast underground oval area between 42nd and 50th Streets. In addition to the track levels, there are also networks of steam-pipe tunnels, ventilation ducts, and storage areas that likely make it the city's most extensive underground structure.
Stories are told of the many underground levels of Grand Central; these stories have only a little truth behind them, as these different "levels" are in fact only steam pipe tunnels, underground water tanks, and similar structures that generally coexist at lowest track level. Nonetheless, it is complex enough that I've been told by one track worker there that he had no idea about the actual extent of the place. It is also true, according to track workers, that until security was heightened in the 1990s, many homeless people would come down to the lower track level to sleep during the winter. This practice is also mentioned in the book Grand Central Winter, by Lee Stringer (Washington Square Press, 1998), although during the winter referred to in the title Lee Stringer usually slept in one of the pedestrian corridors in the station, not in the underground track sections.
One of the more famous stories about Grand Central is that there is a secret entrance to the Waldorf-Astoria hotel from the track level that Franklin Roosevelt used to get from his train to the hotel without being bothered by reporters. This story happens to be true; the entrance was at the end of Track 61, a small spur on the north side of the turnaround. The elevator that once led from this spur into the hotel is now welded shut, however, and the stairway next to the elevator now leads only to the street.
As mentioned above, President Roosevelt (Franklin, not Teddy) used to take a special armored train car from Washington, DC into New York, which would be parked in a section of the lower-level turnaround underneath the station. In order to avoid reporters, the president would then go directly from his special train car to the secret elevator that connected directly to a section of the Waldorf Hotel, several stories above.
These two train cars sit deep underneath Grand Central as if they know the secrets. Could one of them have been the coach that carried the President between the capitol of the US and the capitol of the world?