Yup, remember watching M-Squad as a wee one but in all honesty was too young in that period to realize it was set in Chicago. I think the opening sequence of the police movie genre parody "Police Squad" was a takeoff on M-Squad.
The first time I can remember seeing Chicago immortalized on TV was watching late night showings of the classic "Beginning of the End" starring a pre - Mission Impossible Peter Graves and the always vivacious Peggy Castle. In the film grasshoppers metamorphosize into giant status after eating radioactive grain, develop a taste for human flesh, and then get hoppin' mad and attack Chicago. There were great images of the locusts climbing the Wrigley Building, Merchandize Mart, crossing the draw bridges on the river and hanging around other Chicago landmarks. It was "Must See TV" before there was "Must See TV"
They don't make 'em like that anymore!