Amid weeks of unrest, Catalonians have come together to participate in a centuries-old tradition: human tower building.

Building human towers, or castells, is a popular cultural event in many town festivals in Catalonia and dates back to the 18th century.

This week, to celebrate the Saint Narcís Fair and Festival in Girona, Spain, Catalonians are climbing to new heights.

"Colles," or teams, compete to build the tallest and most complex towers.

Each tower is carefully engineered, with members positioned according to weight and strength. The strongest, heaviest men interlock their arms to form a stable base, saving the lightest, youngest members for the tower's upper levels.

Every team uses different building techniques, resulting in complex patterns when viewed from above.

Teams are considered successful if they can build and deconstruct their towers without a fall. The assembly is complete once all members have climbed into their designated places and the "enxaneta" —a girl normally as young as 5— crowns the top and raises one hand with four fingers held up.

The gesture is said to symbolize the stripes of the Catalan flag. The "enxaneta" then scrambles back down before the whole thing collapses.

Accidents are rare but there have been fatalities. In 2006, a 10-year-old girl fell to her death during a competition in Mataro. The youngest members now wear foam-padded helmets.

This year's 10-day festival in Girona will draw thousands of visitors from around the world, with over 200 events organized in honor of the city's patron saint.