Towers of people

Spain's "Castellers" — Alex Caparros/Getty Images

Members of the "Colla Jove Xiquets de Tarragona" during the construction of a human tower during the 25th Tarragona Castells Competition, in Tarragona, Spain, Oct. 5, 2014.

The "Castellers," who build the human towers with precise techniques, compete in groups, known as "colles" at local festivals. Their goals is to build the highest and most complex human tower.

The Catalan tradition is believed to have originated from human towers built at the end of the 18th century by dance groups.

Tarragona

Members of the "Castellers de Vilafranca" start the construction of a human tower during the 25th Tarragona Castells Competition, Oct. 5, 2014.

Tarragona

Members of the "Castellers de Vilafranca" celebrate after the construction of a human tower during the 25th Tarragona Castells Competition, Oct. 5, 2014.

Tarragona

Members of the "Colla Jove Xiquets de Tarragona" during the construction of a human tower during the 25th Tarragona Castells Competition, Oct. 5, 2014.

Tarragona

A member of the "Castellers de Vilafranca" prepares before the 25th Tarragona Castells Competition, Oct. 5, 2014.

Tarragona

Members of the "Colla Joves Xiquets de Valls" during the construction of a human tower during the 25th Tarragona Castells Competition, Oct. 5, 2014.

Tarragona

Members of the "Colla Jove Xiquets de Tarragona" after the construction of a human tower during the 25th Tarragona Castells Competition, Oct. 5, 2014.

Tarragona

Members of the "Colla Jove Xiquets de Tarragona" celebrate after the construction of a human tower during the 25th Tarragona Castells Competition, Oct. 5, 2014.

Tarragona

Members of the "Colla Joves Xiquets de Valls" start the construction of a human tower during the 25th Tarragona Castells Competition, Oct. 5, 2014.

Tarragona

Members of the "Colla Jove Xiquets de Tarragona" fall down during the construction of a human tower during the 25th Tarragona Castells Competition, Oct. 5, 2014.

Tarragona

Members of the "Capgrossos de Mataro" during the construction of a human tower during the 25th Tarragona Castells Competition, Oct. 5, 2014.

Tarragona

Members of the "Colla Vella dels Xiquets de Valls" start the construction of a human tower during the 25th Tarragona Castells Competition, Oct. 5, 2014.

Tarragona

Members of the "Colla Vella dels Xiquets de Valls" after falling down during the construction of a human tower during the 25th Tarragona Castells Competition, Oct. 5, 2014.

Tarragona

Members of the "Capgrossos de Mataro" fall down during the construction of a human tower during the 25th Tarragona Castells Competition, Oct. 5, 2014.

Tarragona

Members of the "Colla Vella dels Xiquets de Valls" celebrate after the construction of a human tower during the 25th Tarragona Castells Competition, Oct. 5, 2014.