The City of Atlanta Historic Preservation and Urban Design Commission, which is part of the City of Atlanta government, nominates and designates five types of historic properties: Landmark Building or Site, Historic Building or Site, Landmark District, Historic District, and Conservation District. The Atlanta Urban Design Commission was established by city ordinance in 1975. In 1989, the city enacted its current historic preservation ordinance. Since that time, the city has designated more than seventy individual properties and eighteen districts. There are specific criteria for each type of designation.