Cadillac Tower is a Beaux Arts skyscraper in downtown Detroit, notable for being one of the first buildings outside New York and Chicago to rise above 40 floors. It does not have the glamour of the Guardian Building, but it helps tell the same story of early-20th-century ambition in the city centre.
Treat it as an architecture stop while walking between Campus Martius, the Financial District, and the riverfront. The exterior is the point.