Detroit is a large city in Michigan.
Little is known about the history of the city.
They once had a large automotive industry that included US Motors. However, the industry declined and the US Motors factory was abandoned.
Gargoyle and Abomination accidentally unleashed a gamma virus on the city. Donald Blake brought Bruce Banner and Betty Ross there to help. This led to Thor and Hulk teaming up to stop Gargoyle and Abomination.