This one's six people-stories high and climbing! (Jasper Juinen/Getty Images)

It’s a cheerleading pyramid on steroids: the human tower.

You’ll witness the construction of these towers, or castells, in the town squares of Catalonia, Spain. In fact, the tradition of the castell was recently recognized by UNESCO as an “intangible cultural heritage.” So how are these human sandcastles constructed?

As you can see by the pictures, castellers construct towers out of their own bodies, sometimes as many as 10 people-stories high, with each casteller standing on the shoulders of another casteller. The base is supported by a crowd, or pinya, who stand on the ground and push toward the tower. The next few levels of the castell, or the tronc, typically consist of two to five stocky men.

As the tower gets taller, the people get smaller. First younger men and women climb on. And then smaller children take their places at the tippy-top three levels of the tower, or the pom de dalt. The smallest and most nimble child (usually around 5 years of age) climbs the highest. When he or she reaches the top, there’s no pose — no pause for spirit fingers. Just a simple wave, and then he or she slips back down the tower like it’s a fire pole.

So, do these towers ever topple down? Heck yeah, they topple! And ouch! (See video here). Fortunately, the small children who climb to the top wear special helmets that are hard on the inside to protect their heads and soft on the outside to protect other people’s heads, according to the BBC. Watch the video! It’s awesome!

And this is what it looks like when one comes tumbling down:

Look out below! (Jasper Juinen/Getty Images)