The tradition of building castells originated in Valls, near the city of Tarragona, in the southern part of Catalonia towards the end of the 18th century.
A castell is considered a success when stages of its assembling and disassembling, can be done in complete succession. The assembly is complete once all castellers have climbed into their designated places, and the enxaneta climbs into place at the top and raises one hand with four fingers erect, in a gesture said to symbolize the stripes of the Catalan flag. The enxaneta then climbs down the other side of thecastell, after which the remaining levels of castellers descend in highest-to-lowest order until all have reached safety.
Aside from the people who climb to form the upper parts of the tower, others are needed to form the pinya, or bottom base of the castell, to sustain its weight. Members of the pinya (most often men) also act as a 'safety net' if the tower structure collapses, cushioning the fall of people from the upper levels. It is not uncommon—when not in competitions—for other colles to assist in the pinya when a small colla is attempting a specially demanding structure in terms of people needed.
Castells is a representation of how the society should be. Strong at the base, united, in harmony and helping the youngest to raise at the top.