Among the highlights of traditional activities during the Gràcia Festival are the Casteller Days. Castellers are human tower builders, and you can catch them on Friday and Saturday, August 17 and 18. On Friday it's 'castells' built by the Sitges Youth Castellers as guest group, and on Saturday you can watch groups from Reus (the Xiquets), Igualada (the Moixiganguers) and Valls (youth group the Xiquets). The organisation of Castellers invites everyone to participate by forming part of the 'pinya' (literally 'pineapple'), which is the group of people who huddle together around the castellers to give them support in every sense of the word. You're urged to use caution should you decide to take part.