Ever see one of the military bases, and the rows and rows and rows of two-story buildings, all pretty much the exact same and made with very simple construction? Well, those were made in the early stages of World War Two as millions of troops were raised up to go fight Germany, Italy, and Japan. They needed to construct some sort of housing really fast, and so these were made as quickly as possible.

Called "barracks", they were meant for the housing of troops in large open-bay rooms inside. There was a section set aside for showers and toilets, and they all were built the exact same. It was super-simple construction, requiring as few materials as possible and being assembled quickly and with minimal construction training.

They were indeed supposed to be temporary, and get torn down after the war, but tearing buildings down costs money and so it was simpler to just leave them, and use them again if the need arose. These barracks were later used during the Korean War and then Vietnam, getting minor repair work as needed over the years.

Since the 2000's, some of these have finally been getting torn down and replaced with more modern barracks. Brick and cement construction, better plumbing, and some even with small rooms for a handful of soldiers or in some cases, even private rooms (that's pretty rare though). But on a lot of military posts around the country, you can still find these being used, 70 years later.