In the 1940s, America commissioned crucial cargo-carrying "Liberty Ships" for the World War II effort. Hundreds of these 10,500-ton behemoths were needed, but took forever to build: The first took Kaiser Shipyards 253 days to construct. Worse, German U-Boats kept sinking them, meaning more were needed, and as the war continued an impossible order came down: Get the build time down to 105 days. A new manufacturing mindset was required.
By the end of the war, Kaiser engineer Clay Bedford* got the build time down to just 4.6 days per ship, using his radical new manufacturing method. That method was prefabrication. The ship was built in pieces, with multiple crews working simultaneously, then everything was craned into place and connected. That technique, invented under pressure, is still how massive ships like the 183,858-ton AIDAnova cruise liner are built today.
This time lapse of the AIDAnova's construction provides an eye-opening look at the process, starting with the engines. (It is crazy to me that internal combustion engines can be scaled up to this size—the first images below are of the ship's massive V-16. See the dude in the second photo for scale.)