Lessons in leadership and teamwork from Catalonia’s human towers

Catalonia’s tradition of human towers shows how to build legacy, loyalty and leadership, one tier at a time.

In the eastern Spanish city of Valls, there’s a rivalry as entrenched and as charged as any in football: that between the two teams competing against each other to construct the most gravity-defying castells, the human towers that form a vibrant part of Catalonia’s cultural life.

With their respective team shirts separated by a shade of red, the rivalry runs so deep that many members refuse to mention the other team by name and will look away during the other’s performances during competitions. They spy on each other during weekly practices and send out strategy smoke signals to throw the other off track.

“I was so young when I started that it’s in my blood,” says Joan Ibarra, who joined his team, the Colla Vella dels Xiquets de Valls, when he was 8 years old. “I can’t imagine life without castells.”

An activity that is both physically challenging and technically difficult, the unique groups behind the castells provide lessons for leaders looking to create long-term organizations with a strong base and an ambition to touch the sky.

The history of Catalonia’s human towers

The casteller tradition dates back to the end of the 18th century in Catalonia. Originally a coda to a partially religious celebration from Valencia, over time the tower building took on a life of its own.

Valls, a small city south of Barcelona, is home to the two oldest groups or colles: Ibarra’s Colla Vella (founded in 1791 under another name) and the Colla Joves dels Xiquets de Valls (1805).

While their popularity has ebbed and flowed over the centuries, since the early 1980s the number of casteller groups has surged. They were featured in the opening ceremony of the 1992 Barcelona Olympic Games and declared Intangible Cultural Heritage by UNESCO in 2010.

There are now more than 100 colles, mostly clustered around Catalonia but also in places such as China and Australia.

The math behind the towers

Each castell bears a name that resembles a mathematical riddle but is based on three structural elements:

• the number of people in each tier (except the very upper levels, which always have just one or two people);
• the number of tiers;
• whether it has only a ground-level base or additional supporting tiers going up.

Those without the additional supports are called net or freestanding. The minimum number of tiers to be considered a castell is six. A tower only qualifies as completed if it is safely dismantled afterward.

Thus, a “3 de 9 net” is a nine-tier tower with three castellers per tier and no additional support. A “2 de 8 fm” is an eight-tier tower with two castellers per tier and with additional helpers (the “f” and the “m”).

The technical difficulty of a tower depends on its height, the number of castellers per tier (the fewer, the more difficult) and whether or not there are additional people acting as supports for greater stability.

Each tier demands different physical, technical and mental abilities. Children, best suited to the very top because of their light weight, must train to gain the physical agility to quickly scale the tower and the mental strength to overcome their fears and resist panic if a tower begins to wobble. The lower tiers require greater robustness and physical might to withstand the weight of dozens of humans balanced on their shoulders.

Technique and skill are honed through hundreds of hours of practice over the course of a year but especially during casteller season, which runs from spring to fall. Successfully building human towers requires a complex organization that unites, develops and engages hundreds of people: the colles.

Organizations are identity-defining and feel like family

If you have the impression that participating in a human tower is a casual weekend pastime, you couldn’t be more mistaken. The organizations behind the towers, the colles, nurture rivalries as fierce as that between Barca and Real Madrid. Membership can be as identity-defining as nationality; the commitment as encompassing as family.

Colles are nonprofit organizations and all members are volunteers. The Valls-based colles count over 1,000 members each, though not everyone is required to attend every training session, held two to three times per week. The tallest human towers may require 700 to 800 people to build.

A devoted casteller will remember the emotional day they were first awarded the team shirt. Or the event in which they built the most sky-scraping tower. Or the euphoric moment they crowned their city’s most iconic festival.

Colles are intergenerational: it’s not unusual to find a grandparent, parent and child in the mound. A casteller can potentially spend their entire life in the colla, from childhood through to old age. This intergenerational aspect underscores their inclusivity: young children and the elderly have a place in the colla.

Since the 20th century, the incorporation of women — generally lighter in weight and with a different physicality — has allowed for the construction of more ambitious towers.

What began as a working-class activity now draws people from many socioeconomic backgrounds.

“The colla is a heterogeneous group — of ages, of beliefs, of everything,” says Sara Alvarez of the Colla Joves. “We’re very diverse.”

The organization of the colles has grown increasingly complex over the years, involving multiple roles and functions. Most are divided into two main areas:

• A technical area, headed by the cap de colla, in charge of everything related to tower building itself. This includes planning the strategy for each season, technical preparation of the team, management and organization of practices, and leadership of the colla on performance days. Building a castell is technically complex, requiring both careful planning and flawless execution. This is not a trial-and-error process; mistakes can lead to serious injury.
• A social area, headed by the president, who manages all other functions not directly related to tower building. This includes administration, finance, communications, logistics, institutional relations and preservation of the collective memory of the colla.

Complex people management skills

The cap de colla, then, combines the skills of a CEO, a human resource specialist and a head coach. Beyond technical skill in building human towers, strong leadership and people management abilities are required. The cap de colla must understand long-term and short-term strategies, organizational behavior, team dynamics, decision-making and risk management.

At the heart, of course, is the tower. Building the highest and slimmest. Winning the competition held in the town’s main plaza on its patron saint’s day. Beating a key rival. But the goal is not winning a single competition but rather maintaining a high level of performance throughout the season. Choosing when and where to compete and which towers to attempt require careful planning and financial management.

It also requires complex people management. Every member wants to be part of the towers that will define the team’s legacy — and when somebody wins a spot, it means that somebody else has lost theirs.

Every role in a castell matters, but some positions are harder to replace than others, meaning that egos sometimes work against the essential collaborative spirit.

It’s also important to bring in the next generation, requiring a balance between relying on experienced castellers and fostering new talent.

There is also a somewhat counterintuitive career progression for castellers. The most visible element of the tower is the young child who scales people’s backs to the top, but children quickly outgrow that original role. People move into less prominent but more physically demanding roles as they age; or they may opt to form part of the mass of people on the ground providing base support. This downward trajectory can be a challenging and emotional process, and the leader must navigate these transitions with empathy, clarity and leadership.

“We see the full tower and it seems like the top part is the most difficult. But the people that you can’t see, the ones who are at the bottom of the base, that’s a position of the most sacrifice, the most difficult, the hardest to withstand,” says Ibarra.

Beyond this, since tower building is a voluntary activity, it must feel rewarding or else people will drift away. As important as reaching the highest of heights, the central goal of it all is the sense of shared joy.

Leadership lessons

Casteller leaders need the skills of a CEO, a human resource specialist and a head coach

For companies, the colles can offer a lesson in sustaining a different kind of organization. While companies often measure performance by narrow metrics, the castellers define organizational success in broader terms, balancing short-term success with long-term sustainability. Beating a fierce rival in a key competition is part of success, but so is recruiting new talent, developing individual and collective skills, and strengthening a sense of belonging to the organization.

Here are the key leadership qualities:

• People management. Leaning into empathy, leaders must be able to read the mental fitness of the team and its individual members, and provide support when needed. They must manage diverse personalities and abilities within the team and keep them aligned toward achieving team goals. Keeping an eye on the less visible yet crucial members, they must be mindful of the evolving roles of their people over time.
• Ambition and vision. Leaders must set high, motivational goals for the team while managing expectations wisely. They must also be able to articulate a project for the team that encompasses not only the competitive aspect but also the colla’s values, culture, legacy and its contribution to the community.
• Communication. Clear, honest and motivational internal communication keeps the team aligned and informed. At the same time, colles are normally deeply embedded within their communities. The cap represents the group and is often the public face of the colla with media, sponsors, other groups and the broader community.
• Technical knowledge. Although the cap de colla may be supported by a team of experts in specific elements of the tower, such as training children, the leader must be technically proficient in the science behind human tower building. That knowledge enables them to have meaningful discussions with other team leaders as they plan the season.
• Strategic planning. Leaders must translate their vision into actionable steps. This includes both short-term planning, such as preparing for a key performance in the coming month, and long-term planning, including laying out the entire season and beyond. This long- and short-term lens is key to delivering success in the present while securing the future of the organization.
• Risk management. Missteps in tower building can lead to physical injury. A leader must be capable of balancing the need to set ambitious goals against ensuring the safety of the members.
• Tactical decision-making. Leaders must make critical snap decisions on performance days: which towers to attempt or which last-minute substitutions to make. The cap must know how to read the moment — weather, rival performances, the state of the team — and adjust plans strategically to maximize success on any given day. They must be resilient enough to manage the stress of the position and stand firm when making tough decisions.
• Joy. Castells are human connection, cultural preservation, physical defiance — and fun. The leader must maintain a positive mindset and genuine enthusiasm, fostering enjoyment within the team during rehearsals and performances.

MORE INFO: The case study “Castellers: the challenge of touching the sky” is written by Mireia Las Heras, Jose Perez del Valle and Isaac Sastre Boquet, with support from the International Center for Work and Family (ICWF). It is available from IESE Publishing. The case, along with a virtual reality experience and tower-building exercise, is used in executive education workshops at IESE Business School. The innovative teaching module was recognized by the 2025 Financial Times Responsible Business Education Award.

This article originally appeared in the annual publication, Insight for Global Leaders No. 1 (2025).