In Tarragona, hundreds of people are standing on each other's shoulders — for joy

Look closely at the square in Tarragona, Spain, and you'll see a human skyscraper: person on shoulders on person, rising story by story in matching team colors. These are castells, an 18th-century Catalan tradition where whole towns build the tallest, most intricate human towers they can — a teenager's knees wobbling on a grandmother's shoulders, thousands holding their breath below. This weekend's competition drew teams from across Catalonia to test strength, trust, and timing together. It takes one person's weight to know another's completely, and for a few glorious minutes, an entire crowd does exactly that.