At the city of Catolina, Spain; traditional festivals always have great displays of castells which are simply human towers in various shapes and forms. Teams of castellers compete in forming very elaborate towers. A castell, which means castle in the Catalan language, is formed when castellers climb on top of other in successive stages to form the different layers of a castell, which are then disassembled by having the layers collapse on top of each other almost like a falling building.
Castells were listed by UNESCO as one of the Masterpieces of the Oral and Intangible Heritage of Humanity.
They are quite a unique sight to witness. I hope that one day I can see them first hand.