It's an old film, black and white. (1940s or 50s or thereabouts). it's an American film, set in what i THINK was New York City. The main character, male, is working in this skyscraper when there's a black out. he then takes the stairs to get out... shortly thereafter he has amnesia... he doesn't remember/know who he is, and it gets all Twilight-Zone-ish. i'm afraid this is all I remember. Can anyone help?
I believe your thinking of "Mirage" released in (1965) and directed by Edward Dymtryk, with Gregory Peck, Diane Baker, Walter Matthau, Kevin McCarthy, Jack Weston, Leif Erickson, Walter Abel and George Kennedy. It was indeed filmed on location in NYC and was remade as "Jigsaw" in 1968.