Iowa - Criteria: C (architecture/engineering)
| Bellefountain Bridge |
| Belle Plaine Main Street Historic District |
| Bellevue Herald Building |
| Bell, John, Block |
| Benham, F. A., House |
| Benjamin Chapel and Richwoods Cemetery |
| Bennedsen, Boldt, and Hansen Building |
| Bennett Building |
| Bennington No. 4 |
| Benson Block |
| Benton County Courthouse |
| Benton, Richard, House |
| Beresheim, August, House |
| Berg, Henry, Building |
| Bergman, August H., House |
| Berkhimer Bridge |
| Berryhill, Charles, House |
| Bertram Bridge |
| Best, Louis P. and Clara K., Residence and Auto House |
| Best Oil and Refining Company Service Station |
| Bethany Danish Evangelical Lutheran Church |
| Bethel AME Church |
| Bettendorf, Joseph F., House |
| Bevington, C. D. and Eliza Heath, Privy |
| Bevington, C. D., House and Stone Barn |
| Big 4 Fair Art Hall |
| Big Creek Bridge |
| Big Creek Bridge 2 |
| Big Creek Schoolhouse |
| Bigler Building |
| Big Mill Homestead |
| Big Slough Creek Bridge |
| Billingsley-Hills House |
| Binford, Thaddeus, House |
| Bishop's Block |
| Black Hawk County Soldiers Memorial Hall |
| Blackhawk Hotel |
| Black Hawk Hotel |
| Blackhawk State Park, Black Hawk Preserve (Area B) |
| Blackhawk State Park, Denison Beach Area (Area C) |
| Blackhawk State Park, Wildlife Preserve Area (Area A) |
| Blair House |
| Bloedel, Christian, Wagon Works |
| Bloomfield Public Library |
| Bloomfield Square |
| B'nai Jacob Synagogue |
| Boehmler, H. E., House |
| Bohemian Commercial Historic District |
| Bonaparte Pottery Archeological District |
| Boone Bridge 2 |
| Boone County Courthouse |
| Boone River Bridge |
| Boone Viaduct |
| Bostick, William, House |
| Boston Block |
| Bowers and McDonald Office Building |
| Bowman, James W. and Ida G., House |
| Boyd, Byron and Ivan, House |
| Boyle, John R., House |
| Brammer Grocery Store |
| Braska House |
| Brazelton House |
| Brazelton House Hotel |
| Bregant, Jean and Inez, House |
| Bremer County Court House |
| Bricker-Price Block |
| Brick Gothic House |
| Bridge Avenue Historic District |
| Bridge near West Liberty |
| Bridgeport Bridge |
| Broadway-Phelps Park Historic District |
| Brooke Creek Bridge |
| Brookhart, Smith Wildman and Jennie (Hearne), House |
| Brooklyn Hotel |
| Brooks Round Barn |
| Brown Apartments |
| Brown, Corydon, House |
| Brown, James, House |
| Brownlie, Alexander, House |
| Bruce's Snowball Market #1 Addition |
| Bryan, Alden, House |
| Bryn Mawr Apartments |
| Buchanan County Court House |
| Buchanan School |
| Buck Grove Bridge |
| Budde-Singer Building |
| Building at 101 North Riverview Street |
| Building at 1119-1121 W. Third Street |
| Building at 126 South Riverview Street |
| Building at 130-132 North Riverview Street |
| Building at 202 W. Third Street |
| Building at 306 South Second Street |
| Building at 813-815 W. Second Street |
| Burdick, Anthony, House |
| Burg Wagon Works Building |
| Burkam, Elzy G., House |
| Burlington, Cedar Rapids & Northern Passenger Depot-Dows |
| Burlington Depot |
| Burlington Public Library |
| Burlington Railroad Overpass |
Data from United States Park Service and Wikidata
