Wisconsin - Role: Building
| Nathan Strong Park Historic District |
| National Guard Armory 127th Regiment Infantry Company G |
| National Hotel |
| National Tinsel and Toy Manufacturing Company Building |
| Needham, Enoch Gardner and Mary Caroline Koch, House |
| Neenah United States Post Office |
| Neese, Elbert, House |
| Neillsville Masonic Temple Lodge No. 163 |
| Neillsville Post Office |
| Nelson, Charles E., Sr., House |
| Nelson Hall |
| Neosho Village Hall |
| Neufeld, Albert C. and Ellen H., House |
| New Coeln House |
| New Glarus Hotel |
| New Glarus Public School and High School |
| New Glarus Town Hall |
| Newhall Avenue Pump House and Reservoir |
| New Hope Norwegian Evangelical Lutheran Church and Cemetery |
| New Jersey Building |
| New Richmond News Building |
| New Richmond Roller Mills Co. |
| New York Block |
| Nichols, Frank Eugene, House |
| Nichols, John T., and Margaret, House |
| Nickell, William, A., House |
| Nicolet Public School |
| Niedecker, Lorine, Cottage |
| Nieman, Edwin J., Sr., House |
| Nishan, Freda Meyers, Memorial Chapel |
| No. 4 Engine House |
| Noble, Alexander, House |
| Northern Block |
| Northern Casket Company Building |
| North Hall-River Falls State Normal School |
| North Hall, University of Wisconsin |
| North Main Street Bungalow Historic District |
| North Milwaukee High School |
| North Point Lighthouse |
| North, Sterling, House |
| Northwestern Hotel |
| North Wisconsin Lumber Company Office |
| Norton, Pearl C., House |
| Norwegian Buildings at Heg Park |
| Norwegian Evangelic Lutheran Church and Cemetery |
| Notre Dame Church and Goldsmith Memorial Chapel |
| Nunn-Bush Shoe Company Factory |
| Nye, Clark, House |
| Oatman Filling Station |
| O'Brien-Peuschel Farmstead |
| Oconomowoc City Hall |
| Oconomowoc Depot |
| Oconomowoc High School |
| Oconto County Courthouse |
| Oconto Main Post Office |
| Octagon House |
| Octagon House |
| Oehler Mill Complex |
| Ojibwa Courier Press Building |
| Okauchee House |
| Old Ashland Post Office |
| Old Bayfield County Courthouse |
| Old Executive Mansion |
| Old Hospital |
| Old Indian Agency House |
| Old Iron County Courthouse |
| Old Ozaukee County Courthouse |
| Old Plover Methodist Church |
| Old Rock School |
| Old Rock School |
| Old Spring Tavern |
| Old St. Mary's Church |
| Old Synagogue |
| Old U.S. Forest Products Laboratory |
| Old Waukesha County Courthouse |
| Olfson, Peter and Jessie, House |
| Oliver, Joseph B., House |
| Oliver, Owen and Margaret, House |
| Omaha Hotel |
| Omro High School, Annex and Webster Manual Training School |
| Omro Village Hall and Engine House |
| Oneida County Courthouse |
| Oneida Street Station |
| Onion River Flouring Mill/Grist Mill |
| Opera Hall Block |
| Oregon High School |
| Oregon Masonic Lodge |
| Orfordville Depot |
| Oriental Theatre |
| Orpheum Theater |
| Orth, Phillip, Boathouse |
| Orville Beach Memorial Manual Training School |
| Oshkosh Grand Opera House |
| Ottawa House |
| Otter Spring House |
| Ott, John George, House |
| Ott, Will, House |
| Our Lady of Sorrows Chapel |
| Oviatt House |
| Owen High School |
Data from United States Park Service and Wikidata
