When imagining the timeline for constructing a skyscraper, most people probably think in terms of months or even years. But for the Chinese construction firm Broad Sustainable Building, that’s simply too long.

BSB’s newest building, a 57-story tower in Changsha, China, was erected in a mind-blowingly fast 19 days – a rate of three stories per day!

BSB Architect Xian Min Zhang released a promotional time-lapse video showing the construction of the J57 tower – check it out below! (The time-lapse itself begins at around 1:55)

The J57 is a multi-purpose building, containing 800 apartments and office space for up to 4,000 people.

According to Gizmodo, the 80,000-square-meter skyscraper was built entirely out of, “energy-efficient, factory-produced, Lego-like blocks”, making it the world’s tallest prefabricated building.

BSB also took China’s pollution problem into account when constructing the building, using quadruple-thick glass and tight “99.9% sealed” construction to keep air pollution out.

Read more from Business Insider and Gizmodo.