All - Architectural style - Romanesque Revival architecture
| Monona County Courthouse |
| Monon Freight Depot |
| Monroe Avenue Water Filtration Plant |
| Monroe County Courthouse |
| Monroe County Courthouse |
| Monroe County Courthouse |
| Monroe School |
| Montgomery County Courthouse |
| Montgomery County Jail and Sheriff's Residence |
| Montview Boulevard Presbyterian Church |
| Moody Street Fire Station |
| Moore, Dora, Elementary School |
| Moreland House |
| Morrill Hall |
| Morris Building |
| Morris Ranch Schoolhouse |
| Most Pure Heart Of Mary Church |
| Mother of Sorrows Church |
| Mount Moriah Presbyterian Church |
| Mount Morris Bank |
| Mount Pleasant Armory |
| Mount Pleasant Public Library |
| Mount Prospect Baptist Church |
| Mount St. Gertrude Academy |
| Mount Zion Baptist Church |
| M Street High School |
| Mt. Horeb Opera Block |
| Mt. Moriah Baptist Church |
| Mt. Pisgah Lutheran Church |
| Municipal Building |
| Murdock, C.A., Manufacturing Company Building |
| Murdock School |
| Musgrove Block |
| Nagle-Warren Mansion |
| National Bank of Ashland |
| National Bank of Washington, Washington Branch |
| National Brewing Company |
| National Hotel-Wolff Building |
| Nazareth Convent and Academy |
| Neal Clothing |
| Negro Masonic Hall |
| Nelliston School |
| Ness County Bank |
| Netherwood Station |
| Nevada City Free Public Library |
| Nevins Memorial Library |
| Newark Female Charitable Society |
| New Bern Municipal Building |
| Newcomb, Richard F., House |
| New Logus Block |
| New London Public Library |
| New York, Ontario & Western Railway Company Middletown Station |
| New York Presbyterian Church |
| New York State Capitol |
| New Zion AME Zion Church |
| Nichols, Charles E., House |
| Nichols Memorial Library |
| Nicolet Public School |
| Niles Railroad Depot |
| Nissen, S.J., Building |
| Noble County Courthouse |
| Nolin Banking Company |
| Norman County Courthouse |
| Norris, Jewett, Library |
| North Abington Depot |
| North Avenue Presbyterian Church |
| North Easton Railroad Station |
| North Presbyterian Church |
| Notre Dame Church and Goldsmith Memorial Chapel |
| Notre Dame de Chicago |
| Oakdale Public School |
| Oak Street School |
| O'Connor-Proctor Building |
| Oconto County Courthouse |
| Odd Fellows Block |
| Odd Fellows Hall |
| Odd Fellows Hall |
| Odd Fellows Lodge |
| Odd Fellows Lodge and Temple |
| Offerman Building |
| Ogle County Courthouse |
| Ohio Street Methodist Episcopal Church Complex |
| Old Calhoun County Courthouse |
| Old Camden Post Office |
| Old Central Fire Station |
| Old Chicago Historical Society Building |
| Old Courthouse Square |
| Old Delta Democrat Times Building |
| Old Federal Building |
| Old First Church |
| Old Frankfort Stone High School |
| Old Hamilton County Jail |
| Old Interurban Station |
| Old Jail |
| Old Junction City High School |
| Old Land Office Building |
| Old Lawrence City Hall |
| Old Macon Library |
| Old Main |
| Old Main, California State College |
Data from United States Park Service and Wikidata
