Updated

The tradition of building human towers, or castells, dates back to the 18th century and takes place during festivals in Catalonia in northeast Spain.

"Colles," or teams, compete to build the tallest, most complicated towers. The structure of the castells varies depending on their complexity.

Each tower is carefully engineered, with members positioned according to weight and strength. The strongest, heaviest men interlock their arms to form a stable base, saving the lightest, youngest members for the tower's upper levels. Every team uses different building techniques, resulting in complex patterns when viewed from above.

Teams are considered successful if they can build and deconstruct their towers without a fall. The assembly is complete once all members have climbed into their designated places and the "enxaneta" — a girl normally as young as 5 — crowns the top and raises one hand with four fingers held up.

The gesture is said to symbolize the stripes of the Catalan flag. The "enxaneta" then scrambles back down before the whole thing collapses.

Accidents are rare but there have been fatalities. In 2006, a 10-year-old girl fell to her death during a competition in Mataro. The youngest members now wear foam-padded helmets.

Before this week, the highest castell was one containing 10 levels of four people each in 2015.

But this record was beaten Sunday at the 26th Human Tower Competition in Tarragona, when the Castellers de Villafranca team won the final with a 10-level structure having only three people per level. The teams compete over five rounds, with points awarded for height and complexity.

This year's Concurs de Castells in Tarragona was contested by 32 teams from around Catalonia and one from China. A tense final saw the group from Vilafranca del Penedes triumph for the eighth consecutive time.