New York City
When you want gritty realism for your superhero flick, you don't set it in Peoria; you set it in New York.
New York City's shadowy corners and dangerous alleyways are Wade Wilson's stomping ground as a mercenary and Deadpool's playground as an Ajax-hunting vigilante hell-bent on revenge. He's a rough-and-tumble man in a rough-and-tumble city that's chewed up and spit out lesser men. Deadpool's seen things. He's done things. And the film's setting reflects his lack of glossy superhero sheen.
New York is also a place where anything can happen, whether that's dim sum at 3:00 in the morning or being recruited for a top-secret torture program that turns mutants into super soldiers using their DNA and cures metastatic cancer. It's a city that's full of potential, and its underbelly is home sweet home to Deadpool.
Its colorful characters are his family, whether we're talking about Vanessa, the hooker with a heart of gold; Weasel, the bartender at his favorite dive; or Blind Al, the visually impaired senior citizen roommate he found through Craigslist. (Like one does.) Deadpool just fits. He's New York City in human form: volatile, open-minded, moody, and resilient.