How high do you think you could climb? Thousands of people packed the Tarraco Arena in the Spanish city of Tarragona on Sunday for the world's largest human tower competition, marking the 30th edition by showcasing 12 of Catalonia's leading casteller groups. Human towers, known as castells, were inscribed on UNESCO's Intangible Cultural Heritage list in 2010. Tap the link in @BBCNews's bio for the latest news from Europe. #Catalonia #Spain #BBCNews