Castellers Colla Vella Xiquets de Valls form a human tower called "castell" during a biannual competition in Tarragona, Spain, Oct. 5, 2014.

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

Members of the Castellers de Osona complete their human tower during the 25th Human Tower Competition in Tarragona, Spain, Oct. 4, 2014.

Members of the Castellers de la Vella celebrate after finishing their human tower during the 25th Human Tower Competition in Tarragona, Spain, Oct. 5, 2014.

Members of the Castellers Joves Xiquets de Valls try to complete their human tower during the 25th Human Tower Competition in Tarragona, Spain, Oct. 5, 2014.

Members of the Castellers de Terrasa watch as other castellers complete their human tower during the 25th Human Tower Competition in Tarragona, Spain, Oct. 4, 2014.

Members of the Castellers Collas Jove Xiquets de Tarragona fall as they tried to complete their human tower during the 25th Human Tower Competition in Tarragona, Spain, Oct. 5, 2014.

Members of the "Colla Vella Xiquets de Valls" human tower team form a "castell" during the XXV human towers, or castells, competetion in Tarragona, Spain, Oct. 5, 2014.

A girl climbs down as Castellers Colla Jove Xiquets de Tarragona form a human tower, called "castell", during a biannual competition in Tarragona, Spain, Oct. 5, 2014.

Members of the "Castellers de Sants" Human Tower team fall after forming a "castell" during the XXV human towers, or castells, competetion in Tarragona, Spain, Oct. 5, 2014.

Members of the Castellers de Villafranca celebrate after finishing their human tower during the 25th Human Tower Competition in Tarragona, Spain, Oct. 5, 2014.