Fiat's rooftop test/race track in the Lingotto neighborhood of Turin
Unlike Henry Ford's factory line, which went from one end of his huge manufacturing facility to the other, popping out a finished car at the end, Fiat did things a bit different, to say the least. The Lingotto building in Milano was designed by architect Matté Trucco, had five floors, with raw materials going in at the ground floor, and cars built on an assembly line spiraled up through the building. Finished cars emerged at the top level and immediately were driven on the rooftop test track to ensure quality control. Built between 1916 and 1923, it was the largest car factory in the world at that time.
One of the banked turns at the Turin track
This factory was closed in 1982, but public outcry over a plan to demolish the structure caused it to be redeveloped into a more modern use. The structure was turned into a modern public complex containing a shopping mall, concert halls, theater, convention center and a hotel. The work was completed in 1989. The test track was saved, and can still be visited today on the top floor of the shopping mall and hotel.
The spiraled assembly line ramp leading up to the rooftop track in Turin
A scene from the film, The Italian Job from 1969 with Mini-Coopers and police in a car chase on the Fiat rooftop track, curiously, they drove Mini-Coopers and not Fiats.
Fiat also built a test track on the rooftop of its facility in Buenes Aires
A Google Earth view of the current test track in Turin