Catalonia’s human towers are monuments to strength, co-operation and tradition

The Catalan people of northeast Spain have been building massive human towers known as castells since the 18th century. Completed castells can reach nine or ten body-lengths in height, but stay assembled for just a few brief seconds before they’re either dismantled in an orderly fashion or the people of the tower all tumble to the ground. Shot at a competition in the city of Tarragona where castells originated, Casteller is an amazing, occasionally nail-biting look at the tradition, which UNESCO has named a Masterpiece of the Oral and Intangible Heritage of Humanity.