You’ve seen buildings constructed by people, but have you seen them constructed of people? At the beginning of every other October (in even-numbered years), men and women climb on top of each other’s shoulders as part of the astonishing Concurs de Castells (human towers competition) in Tarragona, Spain. Large groups of everyday people from the ages of five to 95 work together to build a living human structure. Watch the castellers climb to create towers reaching upwards of nine stories high in the video above. It will take your breath away in a whirlwind of fear and excitement.

This cultural sport dates back to the end of the 18th century in nearby Valls, when the traditional Valencian dance took off in an upward direction. It took more than 100 years to break the eight-story level, and once it did the sport literally soared. A stunning feat of color coordination and adults and children working together, the event's participants are orderly and ritual as they work towards the top. They have to be, or everything falls apart.

The event was recently recognized by UNESCO as one of the "Masterpieces of the Oral and Intangible Heritage of Humanity," and is one for the bucket list.