The RDO Building is a mixed-use high-rise building located in Downtown Fargo, North Dakota, United States. It became the city's tallest building in 2020, surpassing the Radisson Blu since 1985, and is the second tallest building in the state. The building was formally named Block 9 Tower until the R.D. Offutt Corporation purchased the naming rights of the building. The building is owned and operated by the Kilbourne Group. In addition, the RDO Building contains an expansive programmed community plaza known as Broadway Square, spanning over a half acre.