L
- L-plan buildings (99)
- labor housing (109)
- labor unions (7)
- laboratories (98)
- laborers (24)
- lakes (5)
- lampposts (1)
- landings (marine structures) (2)
- landscape architects (2)
- landscapes (15)
- lateral sewers (1)
- Latin cross buildings (8)
- latrines (7)
- launch complexes (24)
- launching ramps (2)
- launchings (8)
- laundries (12)
- laundry rooms (1)
- laundry (19)
- law & legal affairs (12)
- law enforcement (63)
- law offices (7)
- leather industry (1)
- lecture halls (2)
- legislators (30)
- leisure (5)
- libraries (rooms) (2)
- libraries (50)
- lifeboat stations (4)
- lifesaving stations (6)
- lift locks (17)
- light stations (26)
- lighthouses (30)
- lightships (1)
- lime kilns (10)
- limestone quarries (1)
- Lincoln Highway (8)
- liveries (3)
- livestock loading chutes (1)
- livestock (8)
- living rooms (1)
- loading docks (2)
- lock gates (4)
- locker rooms (5)
- lockers (1)
- lockkeepers' houses (22)
- locks (hydraulic facilities) (67)
- Locks (97)
- locomotive erecting shops (1)
- lodges (28)
- lodging houses (30)
- loft buildings (6)
- log buildings (210)
- log cabins (80)
- log joints (1)
- lumber industry (14)
- lumber sheds (1)
- lumber (17)
- Lutheran churches (11)