CHICAGO — The installation of 20-foot-tall letters spelling out T-R-U-M-P on the side of the billionaire’s gleaming Chicago skyscraper has triggered a war of words between Donald Trump and Rahm Emanuel – with the city’s mayor saying he’s looking for a way to undo the “architecturally tasteless” sign, but the developer is in no mood to take anything down.

The spat pits the abrasive billionaire and relentless self-promoter who turned the words “You’re Fired!” into a personal motto against a mayor who did not get nicknames like “Rahmbo” and “The Rahminator” because he shies away from a fight.

The backdrop is a city that takes its architectural history seriously, where adorning some of the tallest and largest buildings on the planet with the owner’s name is seen as poor form.

“If this sign was in Atlantic City or Las Vegas, nobody would care – but it is in Chicago, and in a part of Chicago full of great buildings from the 1920s to the 1960s and onward,” said Blair Kamin, a Pulitzer Prize-winning architectural critic for the Chicago Tribune

For his part, Trump blames Kamin, whom he calls a “third-rate architecture critic,” for stirring up trouble.

Trump also stressed that he got permission, with the city zoning administrator signing off on it, and the City Council approving it as well.