Church of St. Boniface (Stearns County, Minnesota)
Church of St. Bridget--Catholic (Swift County, Minnesota)
Church of St. James the Less (Philadelphia County, Pennsylvania)
Church of St. Paul the Apostle (New York County, New York)
Church of St. Stephen--Catholic (Stearns County, Minnesota)
Church of the Advent (Spartanburg County, South Carolina)
Historic church in Spartanburg, SC
Church of the Advent (Aroostook County, Maine)
Church of the Ascension (Bristol County, Massachusetts)
Church of the Assumption and Rectory (Shawnee County, Kansas)
Church of the Good Shepherd and Parish House (Hartford County, Connecticut)
Church of the Holy Trinity (Harford County, Maryland)
Church of the Madonna (Bergen County, New Jersey)
Church of the Redeemer (Greene County, Georgia)
Historic church in Greensboro, GA
Church of the Sacred Heart (Richmond, Virginia)
Church of the Saviour and Cemetery (Northampton County, North Carolina)
Church Square (Muscogee County, Georgia)
Church Street Historic District (Middlesex County, Massachusetts)
Churchill Bridge (Oxford County, Maine)
Churchill County Jail (Churchill County, Nevada)
Churchville Presbyterian Church (Harford County, Maryland)
Cincinnati City Hall (Hamilton County, Ohio)
Circulo Cubano de Tampa (Hillsborough County, Florida)
Citizens Bank Building (Yancey County, North Carolina)
Citizens National Bank of Latrobe (Westmoreland County, Pennsylvania)
Citizens' Hall (Hillsborough County, New Hampshire)
Citizens' National Bank (Nobles County, Minnesota)
Citrus County Courthouse, Old (Citrus County, Florida)
City Cemetery (Wake County, North Carolina)
City Hall (Essex County, Massachusetts)
City Hall (Clinton County, New York)
City Hall (Hampden County, Massachusetts)
City Hall (Deer Lodge County, Montana)
City Hall (Berks County, Pennsylvania)
City Hall Historic District (Monroe County, New York)
City Hall Historic District (Lowell) (Middlesex County, Massachusetts)
City Hospital (New York County, New York)
City Hospital Historic District (St. Louis, Missouri)
City National Bank (Tuscaloosa County, Alabama)
City National Bank Building (Harris County, Texas)
City National Bank Building (Stark County, Ohio)
City of Paris Building (San Francisco County, California)
City Park (Denver County, Colorado)
Civic Center Historic District (Denver County, Colorado)
Civic Center Historic District (Kenosha County, Wisconsin)
Civic Institutions Historic District (New London County, Connecticut)
Civil War Monuments in Washington, DC (Washington, District of Columbia)
Civilian Conservation Corps Quarry No. 2 (Pickens County, South Carolina)
Claflin School (Middlesex County, Massachusetts)
Clapp, Charles Q., House (Cumberland County, Maine)
Clapp, George, House (Worcester County, Massachusetts)
Clapp, Lucius, Memorial (Norfolk County, Massachusetts)
Claremont Lower Village District (Sullivan County, New Hampshire)
Clark and McCormack Quarry and House (Stearns County, Minnesota)
Clark Hall, University of Virginia (Albemarle County, Virginia)
Clark Houses (Middlesex County, Massachusetts)
Clark University (Worcester County, Massachusetts)
Clark--Northrup House (Middlesex County, Massachusetts)
Clary Mill (Lincoln County, Maine)
Clayton Banking Company Building (Johnston County, North Carolina)
Clayton County Courthouse (Clayton County, Iowa)
Cleaves, Benjamin, House (Cumberland County, Maine)
Cleftstone (Hancock County, Maine)
Clemson University Historic District I (Pickens County, South Carolina)
Historic college campus district in Clemson, SC
Cleveland Discount Building (Cuyahoga County, Ohio)
Cleveland Grays Armory (Cuyahoga County, Ohio)
Cleveland Law Range (Spartanburg County, South Carolina)
Historic commercial building in Spartanburg, SC
Cleveland Park Historic District (Washington, District of Columbia)
Cleveland Public Square (Cuyahoga County, Ohio)
Cleveland Trust Company (Cuyahoga County, Ohio)
Cliffwood Hall (Penobscot County, Maine)
Cluett Peabody & Company (Worcester County, Massachusetts)
Cobb School (Caledonia County, Vermont)
Cobb, George, House (Worcester County, Massachusetts)
Coburn, Gov. Abner, House (Somerset County, Maine)
Coca-Cola Building (Conway County, Arkansas)
Coca-Cola Building Annex (Fulton County, Georgia)
Cochran, Jehiel, House (Essex County, Massachusetts)
Coddington School (Norfolk County, Massachusetts)
Codman House (Middlesex County, Massachusetts)
Codman Square District (Suffolk County, Massachusetts)
Coghlan Castle (Rolette County, North Dakota)
Cogswell, Edward, House (New London County, Connecticut)
Cohasset Central Cemetery (Norfolk County, Massachusetts)
Cohn House (Sacramento County, California)
Col. Elmer E. Ellsworth Monument and Grave (Saratoga County, New York)
Col. Isaac G. Reed House (Lincoln County, Maine)
Lost to fire April 2, 2017
Colburn House State Historic Site (Kennebec County, Maine)
Colburn Park Historic District (Grafton County, New Hampshire)
Colburn School (Kennebec County, Maine)
Colburn School (Middlesex County, Massachusetts)
Colburn, William, House (Penobscot County, Maine)
Colcord Farmstead (Kennebec County, Maine)
Cold Spring Cemetery Gatehouse (Putnam County, New York)
Cole Block (Oxford County, Maine)
Cole's Hill (Plymouth County, Massachusetts)
Cole, John, Farm (Providence County, Rhode Island)
Colebrook Center Historic District (Litchfield County, Connecticut)
Colgate, Robert, House (Bronx County, New York)
College Avenue Historic District (Outagamie County, Wisconsin)
College Club Inn (Waldo County, Maine)
College Hall (Washington County, Vermont)
College Hall, University Of Pennsylvania (Philadelphia County, Pennsylvania)
Collyer Monument (Providence County, Rhode Island)
Colonial National Bank (Roanoke, Virginia)
Colony House (Cheshire County, New Hampshire)
Colorado Springs City Hall (El Paso County, Colorado)
Colorado Street Bridge (Ramsey County, Minnesota)
Colquitt County Jail (Colquitt County, Georgia)
Columbia City Hall (Richland County, South Carolina)
Columbia House (Washington County, Maine)
Columbia Union Church (Washington County, Maine)
Columbine (Routt County, Colorado)
Columbus High School (Muscogee County, Georgia)
Columbus Investment Company Building (Muscogee County, Georgia)
Columbus Post Office (Columbia County, Wisconsin)
Commerce Building (Ramsey County, Minnesota)
Commercial and Savings Bank (San Joaquin County, California)
Commercial Bank Building (Lac qui Parle County, Minnesota)
Common Burying Ground and Island Cemetery (Newport County, Rhode Island)
Common, The (Knox County, Maine)
Community Building (Rowan County, North Carolina)
Community Building (Essex County, New York)
Community Theatre (Ulster County, New York)
Comstock Covered Bridge (Middlesex County, Connecticut)
One of three remaining covered bridges in Connecticut
Conant Public Library (Cheshire County, New Hampshire)
Concord Civic District (Merrimack County, New Hampshire)
Concord Presbyterian Church (Fairfield County, South Carolina)
Early 19th century church north of Winnsboro, SC
Concord Square Historic District (Middlesex County, Massachusetts)
Confederate Memorial Gateway in Hickman (Fulton County, Kentucky)
Confederate Memorial in Mayfield (Graves County, Kentucky)
Confederate Memorial in Nicholasville (Jessamine County, Kentucky)
Confederate Monument (Portsmouth, Virginia)
Confederate Monument in Augusta (Bracken County, Kentucky)
Confederate Monument in Danville (Boyle County, Kentucky)
Confederate Monument in Frankfort (Franklin County, Kentucky)
Confederate Monument in Georgetown (Scott County, Kentucky)
Confederate Monument in Harrodsburg (Mercer County, Kentucky)
Confederate Monument in Lawrenceburg (Anderson County, Kentucky)
Confederate Monument in Louisville (Jefferson County, Kentucky)
Confederate Monument in Murray (Calloway County, Kentucky)
Confederate Monument in Owensboro (Daviess County, Kentucky)
Confederate Monument in Paducah (McCracken County, Kentucky)
Confederate Soldier Monument in Caldwell (Caldwell County, Kentucky)
Confederate Soldiers Monument (Pulaski County, Arkansas)
Congregational Church of Chelsea (Orange County, Vermont)
Congregational Church of Medway (Penobscot County, Maine)
Conkey-Stevens House (Hampshire County, Massachusetts)
Connecticut State Capitol (Hartford County, Connecticut)
Connecticut Valley Railroad Roundhouse and Turntable Site (Middlesex County, Connecticut)
Stone artifacs of the turntable and roundhouse of the Connecticut Valley RR.
Connor-Bovie House (Somerset County, Maine)
Continental Mill Housing (Androscoggin County, Maine)
Contoocook Mills Industrial District (Hillsborough County, New Hampshire)
Contra Costa County Courthouse Block (Contra Costa County, California)
Control House on 72nd Street (New York County, New York)
Converse Memorial Building (Middlesex County, Massachusetts)
Conway Building (Cook County, Illinois)
Conway Center Historic District (Franklin County, Massachusetts)
Conway County Courthouse (Conway County, Arkansas)
Cony High School (Kennebec County, Maine)
Conyers Residential Historic District (Rockdale County, Georgia)
Cook County Hospital Administration Building (Cook County, Illinois)
Historic abandoned hospital.
Cook's Old Field Cemetery (Charleston County, South Carolina)
Cooke, Amos, House (Providence County, Rhode Island)
Cooke, Noah, House (Cheshire County, New Hampshire)
Cooleemee (Davie County, North Carolina)
Coolidge--Rising House (Spokane County, Washington)
Coombs Covered Bridge (Cheshire County, New Hampshire)
Covered bridge over Ashuelot River on Coombs Bridge Road in Winchester
Coombs, Viola, House (Sagadahoc County, Maine)
Cooper House (Woodford County, Kentucky)
Cooper Library in Johnson Park (Camden County, New Jersey)
Cooper Union (New York County, New York)
Copcutt, John, Mansion (Westchester County, New York)
Copper Falls State Park (Ashland County, Wisconsin)
Corbit-Sharp House (New Castle County, Delaware)
Corcoran Gallery of Art (Washington, District of Columbia)
Corinth National Cemetery (Alcorn County, Mississippi)
Corinth Village (Penobscot County, Maine)
Cornelius Jensen Ranch (Riverside County, California)
Cornell Mills (Bristol County, Massachusetts)
Cornish House (Pulaski County, Arkansas)
Cornucopia (New Castle County, Delaware)
Cornwell Inn (Chester County, South Carolina)
Cosier--Murphy House (Fairfield County, Connecticut)
Cosmos Club (Washington, District of Columbia)
Cottage House Hotel (Morris County, Kansas)
Cotton Mountain Community Church (Carroll County, New Hampshire)