Not for the faint-hearted, castells are human towers that can reach up to 10 stories high – that's 10 groups of people stacked on top of each other!

Cristina Tomàs White and Guifré Jordan join Lorcan Doherty to delve into 'el mon casteller', the world of human towers.

We visit one of the gravity-defying groups in Barcelona, the Castellers de Sants, and chat to Ignasi Escamilla from the Catalan Human Tower Groups Association (Coordinadora de Colles Castelleres de Catalunya).

This week's Catalan phrase is 'fer pinya', which comes from the human tower tradition and means to come together for a common goal, to collaborate.