It’s also the Queen City.
Petaluma, Ca - Armwrestling Center of the Universe
Fort Collins, Co - Home of the Fighting Lambkins
Seattle - The Emerald City
Portland, OR - City of Roses
Jeddah, ‘Mother of the Red Sea,’ ‘The City of Art.’
DO you mean when they pronounce it wrong? Because I always thought “Shy-town” was a great nickname. Also, “The Shy.”
D.C. – “Chocolate City,” but given gentrification this is being replaced by the now more demographically accurate “Drama City.”
–Cliffy
Scranton, PA is known as ‘The Electric City’.
Something about early & widespread use of electricity and the large electric towers along the mountains surrounding it.
(The stuff you learn while eating at Cooper’s…)
Cleveland, OH = C-Town, The Mistake by the Lake, Land of the Cleves
Columbus, OH = C-Bus
Akron, OH = A. K. Rowdy, The Kron
Truckers have interesting nicknames for places, and some of them have become part of the popular vernacular. Here’s a link to some trucker/cb lingo.
Cincinnati is also called the Queen City and/or Porkopolis, at least by locals.
I can’t think of any common nicknames for the cities around here (Tampa, St Petersburg, Clearwater, Sarasota, etc). Maybe “Gods Waiting Room” for St. Pete, although I’ve also heard that for all of Florida.
Rochester N.Y. The Flour/Flower City
The first was from all the mills on the river Genesse.
The second comes from the lilacs.
aka PDX, P-town, Stumptown, Bridgetown, Potland.
Helena, Montana, is the “Queen City of the Rockies.”
Seattle is the Emerald City and (formerly) Jet City.
Toronto is also called the Queen City, as well as Hogtown or The Big Smoke.
Montreal is the City of Saints or la ville aux cent clochers (city of a hundred spires), or la métropole (the metropolis).
Quebec City is la Vieille Capitale (the old capital) or le gros village (the overgrown village).
Also, lest you think that Montreal’s Sin City reputation is recent, I’ve heard that Quebec City was already called “the city of sheep” and Montreal “the city of wolves” … in the 1600s.
Oh yes, and mustn’t forget Winnipeg, aka Winterpeg or The Peg.
I’ve always thought it odd that Chicago is known as “The Windy City” when it’s Boston that’s known as “Beantown”. 
Then there’s Dallas (Texas), which only has “The Big D” to go by. Rather boring and nondescript, but I guess that’s Dallas.
Loaded Dog – why
Indianapolis = The Circle City.
Because it’s in the shape of a circle.
Schenectady, NY: “The Electric City,” or, more grandiosely, “The City that Lights and Hauls the World.” Both very dated, alas.
Warrensburg, NY: “Gateway to the Adirondacks”
Southold, NY: “Oldest English Settlement in New York State.”
Also . . . . “Lake Wobegon: Gateway to Central Minnesota.” 
Macedonia, OH - The Crossroads of Northeast Ohio
(Eh, you’ve never been there. Just passed through I’m sure.)