Logan Simpson is under contract with the Tucson Historic Preservation Foundation (THPF) to conduct research and to write a National Historic Landmark District (NHLD) Nomination for Los Barrios Viejos in Tucson Arizona. The nomination examines numerous barrios (neighborhoods) in historic downtown Tucson. These include previously listed barrios and recommendations for their combined listing, along with newly inventoried resources, as an encompassing National Historic Landmark District. The proposed district contains the highest concentration of Sonoran-style adobe architectural resources within the City of Tucson’s oldest extant barrios, a unique collection of architecture that is singular in the nation. The nomination is in the process of edits and will lead to the listing of the barrios as a National Historic Landmark.