One Campus Martius is a building located in downtown Detroit, Michigan. It began construction in 2000 and was finished in 2003. It has seventeen floors in total, fifteen above-ground, and two below-ground, and has 1,088,000 square feet (100,000 m2) of office space. The high-rise was built as an office building with a restaurant, retail units, space for Compuware and a fitness center, as well as an atrium. The building now has Rocket Mortgage, Microsoft, Meridian Health, Plante Moran and Compuware as its major tenants.

Downtown Detroit is the central business district and a residential area of the city of Detroit, Michigan, United States. Locally, downtown tends to refer to the 1.4 square mile region bordered by M-10 to the west, Interstate 75 to the north, I-375 to the east, and the Detroit River to the south. Although, it may also refer to the Greater Downtown area, a 7.2 square mile region that includes surrounding neighborhoods such as Midtown, Corktown, Rivertown, and Woodbridge.