Iowa - Criteria: C (architecture/engineering)
| 100 Block of West Broadway Historic District |
| 280th Street Bridge |
| Abraham Lincoln High School |
| Abraham Lincoln Statue and Park |
| Adair County Courthouse |
| Adair Viaduct |
| Adams County Jail |
| Adams-Higgins House |
| Adams, Walker, House |
| Adel Bridge |
| Adel Public Square Historic District |
| Adler, E. P., House |
| Agriculture Hall |
| Ainsworth, William W. and Elizabeth J., House |
| Albertus Building |
| Albia Square and Central Commercial Historic District |
| Albright Bridge |
| Albright House |
| Alden Bridge |
| Algona Junior and Senior High School Building and High School Building Annex |
| Alhambra Apartments |
| Allamakee County Courthouse |
| Allee, Jesse J. and Mary F., House |
| Allen, G. W. S., House |
| Allen House |
| Allen, James, Stone Barn |
| All Saints Catholic Church |
| Alsop, Carroll, House |
| Alumni Hall |
| Ambler, Henry, House |
| Ambrose Hall |
| American Express Building-Carroll |
| American House |
| American Republic Insurance Company Headquarters Building |
| American Telephone & Telegraph Co. Bldg. |
| Ames Creek Bridge |
| Ames High School |
| Ames Main Street Historic District |
| Anamosa Main Street Historic District |
| Anamosa Public Library |
| Anderson, D. H., Building |
| Anderson, D. H., House |
| Andrew-Ryan House |
| Andrus, A. J., Duplex |
| Ankeny Building |
| Anthony, Horace, House |
| Antioch School |
| Appanoose County Courthouse |
| Appanoose County Sheriff's House and Jail |
| Apperson-Iowa Motor Car Company Building |
| Architecture of Henry K. Holsman Historic Campus District |
| Argyle Flats |
| Armstrong, George and Susan Guiberson, House |
| Armstrong, Robert and Esther, House |
| Arthur, Thomas, House |
| Ashby, Atchison A., House |
| Ashby Manor Historic District |
| Ash Park Historic District |
| Ashton, Ned, House |
| Atchison, Topeka and Santa Fe Passenger and Freight Complex Historic District |
| Atlantic High School |
| Audobon County Court House |
| Ausadie Building |
| Averill, A. T., House |
| Averill, Glenn M. and Edith, House |
| Avery Theater, The |
| Ayrshire Apartments |
| Backbone State Park Historic District |
| Badgerow Building |
| Baird, E. J., House |
| Baker, C. H., Double House |
| Ballard, John W., House |
| Ball, Dr. J. O. and Catherine, House |
| Ball-Waterman House |
| Ball, W. C., House |
| Bandshell Park Historic District |
| Bangs, John and Lavina, House |
| Bank of Sumner |
| Banta, J. V., House |
| Baptist Church |
| Barkley, Alonzo J. and Flora, House |
| Barrows, Edward S., House |
| Bartlett, Walter M., Double House |
| Basilica of St. Francis Xavier, Church and Rectory |
| Bassnett-Nickerson House |
| Bates Park Historic District |
| Baum, William A. and Etta, Cottage |
| B Avenue NE Historic District |
| Baxter, H.A., Coal Company Historic District |
| Beaver Creek Bridge |
| Beaver Creek Bridge |
| Beck, James A., House |
| Bedford Commercial Historic District |
| Bedford Oil Company Station |
| Bedford Public Library |
| Beeds Lake State Park, Civilian Conservation Corps Area |
| Beeson, Byron A., House |
| Belfrage, W.L. and Winnie (Woodford), Farmstead Historic District |
| Belknap, Gen. William Worth, House |
| Bell, Alvin Bushnell, House |
Data from United States Park Service and Wikidata
