The video: There are rush construction jobs, and then there's the new Ark Hotel near Dongting Lake in China's south-central Hunan province. Chinese sustainable-building firm Broad Group built the entire 30-story, 183,000-square-foot building in 15 days. That's a mere 360 hours. (Watch a time-lapse video below.). The hotel was built at a fraction of normal Chinese construction costs, with no worker injuries. And the building isn't flimsy: It is built to withstand a 9.0-magnitude earthquake, and energy-efficient to boot.  

The reaction: Fifteen hours! exclaims Jesus Diaz at Gizmodo. I couldn't stop watching this "amazing" video "in disbelief." Building a 30-story tower in 360 hours is "rather impressive," says Adam Barnes at The Economist. But the devil's in the details. That 360 hour figure doesn't include the time it took to build the foundation or, crucially, all the prefabricated parts. "So the claim to a 15-day construction period should not be taken too seriously." But it's the prefab aspect that makes this project so "completely amazing," says Lloyd Alter at Treehugger. The "incredibly clever" design allows everything to be built in factories beforehand, anywhere, then assembled quickly and super efficiently. "The architectural and construction world just changed." Watch the magic unfold: