[jtcond13]

My favorite Grand Central easter egg is the 'Whispering Arch' by the Oyster Bar. Standing in one corner, you can speak into the wall and be heard by someone standing in the opposite corner.

http://www.sonicwonders.org/whispering-walls-grand-central-s...

[Rickasaurus]

I remember standing there and wondering why people kept coming up and pressing their faces against the wall.