The Town of Rietbrock is located in Marathon County, Wisconsin, United States. It is part of the Wausau, WI Metropolitan Statistical Area. The town contains one of the four 45×90 points of the world, where the 45th parallel north and 90th meridian west intersect. The population was 981 at the 2010 census. The unincorporated communities of Poniatowski and Schnappsville are located within the town.

Marathon County is a county located in the U.S. state of Wisconsin. As of the 2020 census, the population was 138,013. Its county seat is Wausau. It was founded in 1850, created from a portion of Portage County. At that time the county stretched to the northern border with the upper Michigan peninsula. It is named after the battlefield at Marathon, Greece.