Wikipedia: "A castell is a human tower built traditionally in festivals at many locations within Catalonia, Spain. At these festivals, several colles castelleres or teams often succeed in building and dismantling a tower's structure. On November 16, 2010, castells were declared by UNESCO to be amongst the Masterpieces of the Oral and Intangible Heritage of Humanity.
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. Later it developed a following in other regions of Catalonia and, since 1981, when the first castell of 9 levels of the 20th century was built, it has become very popular in most of Catalonia and even the Balearic Islands. The only 6 teams that have built complex gamma extra castells are from Valls, Vilafranca del Penedès, Terrassa, Mataró and Tarragona."