The Lingotto Building in Turin was, when it was built, the biggest car factory in the world. The Lingotto Building was unusual in that it had five floors, with raw materials going in at the ground floor, and cars built on a line that went up through the building. Finished cars emerged at rooftop level, where there was a rooftop test track.
The building is no longer a factory but a modern complex of concert halls, theatre, convention centre, shopping arcades and a hotel.
View a video of the Lingotto Building on Google Maps