Maryland - Criteria: C (architecture/engineering)
| Catonsville Historic District, Old |
| Caves Valley Historic District |
| Cecil Apartments |
| Cecil's Mill Historic District |
| Cedarcroft Historic District |
| Cedar Grove |
| Cedar Grove |
| Cedar Grove |
| Cedar Hill |
| Cedar Hill |
| Cedar Park |
| Central Catonsville and Summit Park Historic District |
| Centreville Armory |
| Centreville Historic District |
| Chamber of Commerce Building |
| Chambers Park Log Cabin |
| Chanceford |
| Chapel Hill Historic District |
| Chapel of the Incarnation |
| Chapline, William, House |
| Charlcote House |
| Charlestown Historic District |
| Charles Village-Abell Historic District |
| Charlotte Hall Historic District |
| Chase-Lloyd House |
| Chautauqua Tower |
| Cherry Grove, HO-1 |
| CHESAPEAKE (lightship) |
| Chester Hall |
| Chestertown Armory |
| Chestertown Historic District |
| Chestertown Railroad Station |
| Chesterville Brick House |
| Chestnut Ridge |
| Childs Residence |
| Chiswell's Inheritance |
| Chizuk Amuno Synagogue |
| Choate House |
| Christ Church |
| Christ Church |
| Christ Church |
| Christ Church, Graveyard and Sexton's House |
| Christ Church Guilford |
| Christ Episcopal Church |
| Christ Episcopal Church and Cemetery |
| Churchill Threatre-Community Building |
| Churchman, John, House |
| Church of the Holy Trinity |
| Churchville Presbyterian Church |
| Citizens State Bank |
| City Hall |
| Clagett House at Cool Spring Manor |
| Clarke, Littleton T., House |
| Clark's Conveniency |
| Clay's Hope |
| Clifton |
| Clifton Park Valve House |
| Cloisters, The |
| Clover Hill |
| Coca-Cola Bottling Company of Baltimore Building |
| Cockey-Jamison-Hendrickson House and Store |
| Coffren, John W., House and Store |
| Cold Saturday |
| Coldstream Homestead Montebello Historic District |
| College Heights Estates Historic District |
| College of Medicine of Maryland |
| College Park Airport |
| Collins, Jackson, House |
| Colonial Annapolis Historic District |
| Colonial Theatre |
| Colora Meetinghouse |
| Commercial Credit Company Building |
| Compton |
| Compton Bassett |
| Concord |
| Content |
| Content |
| Cool Hollow Home |
| Corbett Historic District |
| Cornehill |
| Costen House |
| Cottage, The |
| Coventry Parish Ruins |
| Craighill Channel Lower Range Front Light Station |
| Craighill Channel Lower Range Rear Light Station |
| Cray House |
| Creagh, Patrick, House |
| Creedmore |
| Cresap, Michael, House |
| Crisfield Armory |
| Crisfield Historic District |
| Crockett House |
| Crooked Intention |
| Cross Manor |
| Cross Roads Church |
| Crum Road Bridge |
| Cullen Homestead Historic District |
| Cumberland YMCA |
| Cummins Memorial Church |
| Curtis-Shipley Farmstead |
Data from United States Park Service and Wikidata
