M
- machine industry (7)
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- maintenance (27)
- makers' marks (1)
- mangers (1)
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- mansard roofs (18)
- mansions (81)
- mantels (10)
- manufacturing (56)
- manure bins (1)
- maps (10)
- marble quarries (1)
- marinas (1)
- marine terminals (4)
- markers (monuments) (5)
- markets (29)
- masonic buildings (49)
- masonry (building materials) (2)
- masonry (12)
- mass transit (15)
- mausoleums (14)
- meat industry (27)
- meat processing plants (3)
- mechanical engineering (10)
- medical aspects of war (20)
- Medical College ()
- Medical Dispensary ()
- medical education (8)
- Medical Facility ()
- Medical Hospital ()
- Medical Laboratory ()
- medical offices (20)
- Medical offices (20)
- medical personnel (2)
- Medical Shop ()
- Medical Storage ()
- Medical Supply ()
- Medical/Triage ()
- Medicine Factory ()
- medicine (66)
- Medieval architectural elements (1)
- Mediterranean Revival architectural elements (4)
- Meeting Hall ()
- Meeting houses (106)
- meeting houses (106)
- Meeting House ()
- Meetinghouse ()
- Memorial Building ()
- Memorial Chapel ()
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- Memorials (66)
- memorials (66)
- Memorial ()
- Men's Infirmary ()
- Mennonite Meetinghse ()
- mental institutions (2)
- Mental Ward ()
- Mercantile facilities (5)
- mercantile facilities (5)
- Mercantile Store ()
- Mercantile (5)
- Merchandise Plant ()
- Merchandising ()
- Merchant's Exchange ()
- Merchants Exchange ()
- merchants' exchanges (3)
- Merchants' exchanges (3)
- mercury mining (3)
- Mesa Verde (1)
- Mess Hall/Galley ()
- Mess halls (51)
- mess halls (51)
- Mess Hall ()
- metal buildings (45)
- Metal buildings (45)
- metal cladding (1)
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- Metal mining ()
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- metal truss bridges (54)
- Metal truss bridges (54)
- metallurgical industry (33)
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- metalworking (18)
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- meteorology (1)
- Meth Epis Church ()
- Meth Epis Parsonage ()
- Meth Episc Church ()