The tradition of building human towers or "castells" dates back to the 18th century and takes place during festivals in Catalonia, where "colles" or teams compete to build the tallest and most complicated towers.

"Castells" were declared by UNESCO one of the Masterpieces of the Oral and Intangible Heritage of Humanity.

Here is a gallery of the 27th Human Tower Competition in Tarragona, Spain by Chief Photographer for the Associated Press in Spain and Portugal Emilio Morenatti.

Photos by Emilio Morenatti