That was no time warp at Borough Hall on Monday.

Those men donning fedoras and long wool coats — the height of fashion in the 1920s — were merely on hand to film a scene from the upcoming HBO drama “Boardwalk Empire.”

The show, set in Atlantic City during Prohibition, was in town to shoot a scene involving a press conference on the steps of the venerable Downtown seat of government.

Don’t look for the scene any time soon; the show, produced by Terence Winter (“The Sopranos”), doesn’t debut until this fall.