National Register of Historic Places:The official site provides a searchable database of properties on the Register, information on listing, virtual tours of historic sites, resources for teaching, and order form for its publications.
American Architecture: 1700 to 1799: Some of the famous buildings of eighteenth-century America featured in Great Buildings Online: images, architects, commentary and sources.
American Jewish Sites Database: The International Survey of Jewish Monuments provides a searchable database of information on historic Jewish sites in North America, including synagogues, cemeteries and houses.
American Landscape and Architectural Design, 1850-1920: A collection of 2,800 lantern slides from the Harvard Graduate School of Design, housed by the Library of Congress. Views of cities, specific buildings, parks, estates and gardens.
Built in America: The Library of Congress Historic American Buildings Survey and Historic American Engineering Record. Searchable database of images.
Digital Archive of American Architecture: Images of American architecture from 1620 to the present by Prof. Jeffery Howe of Boston College.
Historic American Building Survey and Historic American Engineering Record: An index of architectural and engineering sites organized by state, some with images.
How to Research Architecture: A beginner's guide by the New York Public Library, particularly relevant for users of that library and buildings in New York.
Mission 66 Visitor Centers: Christine Madrid discusses and illustrates the visitor centers built in US national parks 1956-1966 as examples of early modern, distinctly American architecture.
Paper Models of Buildings: Bruce Roffi displays his models of some historic American buildings alongside photographs and brief histories of the originals.
Researching the History of Your House: A bibliography and links provided by David L. Langenberg for the American Library Association's Reference and User Services Association, History Section.
The Architecture of Colonial New England and the Southern Colonies: Lecture and bibliography by Valerie Ann Polino of Yale-New Haven Teachers Institute on the development of architecture in Colonial America.
The Evolution of the American Front Porch: A study by Scott Cook with illustrations and a bibliography. Covers its origins, stylistic evolution, history and cultural significance.
The Lustron Connection: Ron Allen presents a history, registry and photograph gallery of Lustron steel homes built in the US between 1949 and 1950 for returning servicemen.
World Heritage Sites in the United States: The National Park Service and US/ICOMOS offer a list of sites of cultural and natural interest already nominated and waiting for review. Criteria for site nominations.