Wisconsin - Criteria: C (architecture/engineering)
| "Milwaukee-Downer ""Quad""" |
| Milwaukee Normal School-Milwaukee Girls' Trade and Technical High School |
| Milwaukee Pierhead Light |
| Milwaukee Road Depot |
| Milwaukee Road Passenger Depot |
| Mindoro Cut |
| Miramar Drive Residential Historic District |
| Mission House Historic District |
| Mitchell Building |
| Mitchell Lewis Building |
| Mitchell-Rountree House |
| Moffat, John S., House |
| Monfils, Joseph, Farmstead |
| Monroe Commercial District |
| Monroe County Courthouse |
| Monroe Water Tower |
| Montello Commercial Historic District |
| Moon, D. R., Memorial Library |
| Moquon Town Hall and Fire Station Complex |
| Mottley Family Farmstead |
| Mt. Horeb Opera Block |
| Mueller-Wright House |
| Muirdale Tuberculosis Sanatorium |
| Murphy Farms Number 1 |
| Murray, George, House |
| Myers, Peter, Pork Packing Plant and Willard Coleman Building |
| Naeset, Jens, House |
| Nakoma Historic District |
| Namur Belgian-American District |
| Nashold 20-sided Barn |
| Nathan Strong Park Historic District |
| Near East Side Historic District |
| Neenah United States Post Office |
| Neillsville Downtown Historic District |
| Neillsville Masonic Temple Lodge No. 163 |
| Neillsville Post Office |
| Neillsville Standpipe |
| Neufeld, Albert C. and Ellen H., House |
| Newberry Boulevard Historic District |
| New Richmond West Side Historic District |
| NIAGARA (steamer) |
| Nichols, John T., and Margaret, House |
| Nicolet Public School |
| Nieman, Edwin J., Sr., House |
| No. 4 Engine House |
| Nohl, Mary L., Art Environment |
| NOQUEBAY (Schooner-Barge) Shipwreck Site |
| North Broadway Street Historic District |
| North Grant Boulevard Historic District |
| North Hall-River Falls State Normal School |
| North Michigan Street-North Superior Street Historic District |
| North Point Lighthouse |
| North Point South Historic District |
| North Point Water Tower |
| North Sherman Boulevard Historic District |
| North Third Street Historic District |
| North Washington Street Historic District |
| Northwestern Branch, National Home for Disabled Volunteer Soldiers Historic District |
| Northwest Side Historic District |
| Norwegian Evangelic Lutheran Church and Cemetery |
| Notre Dame Church and Goldsmith Memorial Chapel |
| Oak Creek Parkway |
| Oakland-Dousman Historic District |
| Oatman Filling Station |
| O'Brien-Peuschel Farmstead |
| Oconomowoc City Hall |
| Oconomowoc Depot |
| Oconto County Courthouse |
| Octagon House |
| Octagon House |
| Okauchee House |
| Old Ashland Post Office |
| Old Bayfield County Courthouse |
| Old Executive Mansion |
| Old Fourth Ward Historic District |
| Old Indian Agency House |
| Old Iron County Courthouse |
| Old Main Street Historic District |
| Old Ozaukee County Courthouse |
| Old Plover Methodist Church |
| Old Rock School |
| Old Rock School |
| Old Spring Tavern |
| Old St. Mary's Church |
| Old U.S. Forest Products Laboratory |
| Old World Third Street Historic District |
| Omro Village Hall and Engine House |
| Oneida County Courthouse |
| Oneida Street Station |
| Oregon High School |
| Oregon Masonic Lodge |
| Oregon Water Tower and Pump House |
| Orfordville Depot |
| Orpheum Theater |
| Orth, Phillip, Boathouse |
| Orton Park Historic District |
| Orville Beach Memorial Manual Training School |
| Oshkosh State Normal School Historic District |
| OTTAWA (Tug) Shipwreck Site |
| Ott, John George, House |
Data from United States Park Service and Wikidata
