You're looking at human structures, comprised of contortionists competing for the best tower made of people. The event takes place once every two years in spain and it's called Concurs de Castells.

The last event took place on October 6 and 7 where a total of 32 teams gathered to participate. These images come courtesy of Spanish photographer, David Oliete, who captured all of the action up-close.

Teams are judged based on points, and the higher and more complex the tower the more points each is awarded. Each tower consists of between 100 and 500 women and men that reach heights of six to ten "stories."

David Oliete, via Design Boom