I’VE NEVER TOTALLY UNDERSTOOD why New York is known as “the Big Apple.” Why an apple? There’s nothing particularly apple-y about New York. If the point is just to call it a “big” something, why not choose something that people associate with the city? “The Big Sludge,” for example, is a better description of New York, especially in the late winter.
Here Are the Stories Behind the Nicknames of the World's Greatest Cities
Turns out, there’s a story behind the nickname. The good folks at Just the Flight put together this excellent infographic on the stories behind the nicknames of the world’s great cities. Some of them are pretty self-explanatory, but others will surprise you. 
Courtesy of Just The Flight