A castell is a human tower built traditionally in festivals at many locations within Catalonia, Spain. At these festivals, several colles de castelleres or teams often succeed in building and sustain a tower's structure for a certain length of time. The tradition of building human towers 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 even Majorca, and currently has become very popular in parts of Spain. However, the best and most skilled castellers are still found near Tarragona.