Human tower-building is the ultimate team sport. A single structure, or castell, can comprise hundreds of individuals working together to ascend several stories in the air. The unusual tradition traces back to the 18th century and, as CBS News reports, the 26th competition recently took place in Catalonia, Spain.

To win the event, teams called colles must assemble to build the tallest most complex castells possible. The towers can involve as many as 400 people and reach dizzying heights. The world record for tallest tower belongs to the team Minyons de Terrassa, which stacked competitors 10 levels high during 2015’s event. The construction process is only half the battle. After the colles achieve their maximum height, they then have to disassemble themselves without toppling over.

According to Times of Malta, roughly 20,000 people gathered to witness the competition. This year the Castellers de Villafranca team was crowned victorious, marking their eighth win in a row.

Lluis Gene/Getty

Lluis Gene/ Getty

David Ramos/Getty

David Ramos/Getty

David Ramos/Getty

[h/t CBS News]

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