Detroit Assembly (also known as Detroit Cadillac, Cadillac Assembly or Clark Street Assembly) was a General Motors automobile factory in Detroit, Michigan on Clark Street, south of Michigan Avenue (U.S. Route 12). It began operations in 1921 and Cadillac bodies were supplied by Fleetwood Metal Body in 1921 after Fisher Body assumed operations. It was the second location that built Cadillacs, when Cadillac originally started out as the Henry Ford Company which was located at the intersection of Cass Avenue and Amsterdam Street. Engine block and cylinder heads were cast at Saginaw Metal Casting Operations then assembled at Tonawanda Engine before delivery to Detroit Assembly for installation.