20th-century fortifications

line of fortifications along the French/German border

thumb|Completed in 1750, Fort Edward (Nova Scotia)|Fort Edward, Nova Scotia in Canada is the oldest remaining military blockhouse in [[North America.]] thumb|upright|Reconstructed European wooden [[keep at Saint-Sylvain-d'Anjou, France, has a strong resemblance to a North American western frontier log blockhouse]]

concrete dug-in guard posts, normally equipped with loopholes through which to fire weapons

architectural structure

defence line in Russia

underground WW2 bunker complex, Japan

aspect of history