Watch: tumbles and triumphs at the 'human castles' festival of fear

The small girl, no more than six, climbs steadily toward the eight-person-high summit. 

She moves purposefully, like a monkey up a tree, over the backs and shoulders of team mates with shaky knees and strong arms. As she reaches the top she crouches and quickly raises a trembling, but triumphant hand to the cheering crowd. Now all she has to do is get down.

Castells, or human castles or towers, have been around more than 200 years but the spectacle never gets old. 

Following the castellers’ motto of “For?a, equilibri, valor i seny”, or “Strength, balance, courage and common sense,” the Catalonian tradition sees collas, or teams, build physics-defying towers from hundreds of members of their town. 

At the base, baixos squish together and pray the tower won’t collapse on them. The tight scrum – eight or nine people deep – supports the second tier segons to stand. Ter?os stand on their shoulders and so on up the tower. The largest towers have 10 tiers, each consisting of two, three or four people.

Wearing helmets, the smallest members take the highest positions with the nimble enxaneta – a child as young as five or six – tasked with the heart-stopping scramble to the top.

Tarragona, a port city 62 miles south of Barcelona with cobblestone streets and Roman ruins, hosts the biennial Concurs de Castells festival. The competition brings together the best collas from across Catalonia to build the tallest and most complex towers. 

In a renovated former bullring, the floor is a chattering mass of colour. Colla members wear a shirt in their team colour, sky or dark blue, red, yellow, purple, orange or one of three shades of green, with white trousers and often a bandana or neckerchief.The stadium floor looks like a multicoloured pie and each colla has claimed their slice. Teammates tightly wrap one another’s waists in black fabric. This sash, called a faixa, acts as a crucial foothold for climbers. 

One of the Tarragona teams begins their build. The baixos are called into position first by the colla captain. They link their arms over the person in front and pack in tighter than rush hour commuters on the London underground. Should the tower collapse, this will be the net that catches those who fall. 

As the next tiers emerge, clambering over shoulders and heads with the deliberate steps of a cat stalking prey, it is clear castells is a game the whole community can play. There are barrel-chested men, who wouldn’t look out of place in a rugby front row, alongside smaller and older (some well into their 70s) men and women. Up the tiers the participants become slender but still strong – even the fifth or sixth tier must bear the weight of potentially several people standing on their shoulders.

As the tower grows, the slightest members wriggle up the legs and backs of their larger colleagues as quickly as they can, aware the weight of the town – part of it, literally – is on their shoulders.

The enxaneta nears the summit and the blue sky peeking through the 32-metre-high stadium roof reminds the gasping crowd how high she is. At the point of the pyramid she rolls on to her teammate, who looks younger than 10, before sliding down the backs below to safety.

Jordi Pallarès, a fourth generation casteller from Valls, the town where the tradition began, climbed his first castell aged six and is still involved 27 years later.

“I was scared and sometimes I didn’t want to climb. Luckily, no one forced me. In the end, courage is not to not be afraid, but to know how to confront your fear,” he says.

“The tradition is my life and the colla is my second family.”

As one castell finishes, in a flurry of fist pumping and a roar from the crowd, another begins. The youngest have reached the halfway point when the tower wobbles. Those on the second and third tiers grit their teeth and grip the shoulders of their partner opposite. They tell their knees not to buckle. There is a shout from below. The two youngest retreat, slithering down the tower and lightly hoping from the base into the arms of relieved-looking mothers.

Tower collapses are not uncommon but serious injuries are rare. The descent is considered the most treacherous part (castells are awarded points for completing a build and more for successfully dismantling it).

Pallarès has an 18-month-old daughter and would like her to continue the family tradition when she’s older.

“Castells teach children to work in a team, trust in others, respect, ambition, effort and sacrifice,” he says.

For the watching parents, crowd and community, it is a source of pride to see their smallest touch the sky. And, when their feet return to the ground, everyone can breathe again.

For more information on how to attend one of the "human towers" festivals, visit tarragonaturisme.cat.