Castellers from Catalonia perform on Nanjing Road E.

A team of more than 200 castellers has been building spectacular human towers every day at Europe Square at Expo 2010 Shanghai during Catalonian week celebrations.

A series of events, which end on May 30, are being held to celebrate this region of Spain, highlighting food, culture, education and investment opportunities. But the castellers are undoubtedly the most popular.

This is the first time a team of castellers has performed in China.

A castell is a human tower built traditionally at festivals in Catalonia. At these festivals, several castell teams, build and sustain a tower structure for a certain period of time.

The group at the Expo, La Colla Vella de Valls, is among the top three of the six major castell teams in Catalonia. The team performed at the opening ceremony of the 1992 Barcelona Olympic Games.

Catalonia, with its capital city of Barcelona, is located in Northwest Spain. It is one of the most economically developed regions of the country, said Jordi Fortuny Batalla, representative of the Generalitat de Catalunya.

Wearing pink shirts, white pants and black waist sashes, castellers gather at 11 am and 6:30 pm every day in the middle of Europe Square to form the base of the tower.

Other team members then climb on their shoulders one after another. When the tower of six levels is formed, with three to four people on each level, a young child climbs to the top of the tower and raises his/her hands to announce the completion of the structure. The castellers then dismantle the tower by climbing back down to the ground.

Once the base is formed, the structure is completed in only three to four minutes. A castell can be a Cinc - with five people on each level, Quatre - four on each, Tres - three on each, Torre - two on each, or Pilar, with only one person on each level.

The Pilar is especially difficult, as each casteller has to work on his own to support those on top of him and keep balance.

To build a Pilar, castellers form a Cinc or Quatre, then climb down until only one person remains on each level.

Sarai, 5, one of the girls climbing to the top of the formation, became involved in castells when she was just three. She dismissed the danger of standing on top of the tower, 12 meters in the air, saying she was "happy" and "felt well".

"Sometimes accidents happen and the tower collapses, but those on top are not likely to get injured because they always fall on the people who make the base," said Teresa Amenos, wife of the team leader. The child who climbs to the top of the tower wears a helmet specially designed for the castellers, Amenos said.

A band of about eight people play traditional Catalonian music with Gralla nad drums to encourage the castellers. They also give instructions, as those on the base level can't look up and see the progress of the tower.