Metro City (Riverton, Michigan in the live action films) is a city with buildings resembling those from Pittsburgh or New York. At one point, it was declared "America's Safest City" when Dr. Claw and all the criminals were behind bars. It's notable residents are Inspector Gadget, Penny, Brain, and Chief Quimby.
Apparently, Metro City is infamous for Dr. Claw and his M.A.D. Agents constantly trying to take over it, with Gadget always foiling his plans. The city is located in Canada.