From the 2012 Concurs de Castells, a human tower-building competition in Tarragona, Spain, watch this video by photographer David Oliete. David also took photos.

A long tradition in the region, castells began at the end of the 18th century. The sport has rules, techniques, and team responsibilities to guard safety and success. The pinya or base is made of a few hundred people that can catch anyone who falls, and the tower itself has a variety of different formations. The top three levels are the pom de dalt, made up of children in helmets. 

While the video above doesn’t show some of the more harrowing challenges, this video by Mike Randolph in 2010 captures why safety and teamwork are so important:

via DesignBoom.

With a cameo by Forest Scientist Stephen Sillett, watch this behind the scenes video about photographing the world’s second-largest known tree, 3,000+ year old President, in Sequoia National Park.

The resulting image, made from 126 images by photographer Michael “Nick” Nichols, is featured in National Geographic’s December 2012 issue.

Meet Forest Scientist Stephen Sillett. He has dedicated his life to studying the Redwood Forest canopy, 350 feet high into a separate world in the tops of the tallest and oldest trees on the planet.

Stephen and his team ended up finding much more than they were expecting: an environment where fruit grows and where small animals never touch the ground, all with a humbling view. And now they’re on a quest to measure and learn more about these ancient giants. 

Watch more about Stephen’s work in KQED’s Science on the Spot:

Following photographer and mountain climber Jimmy Chin on assignment for National Geographic.