Chicago Mayor Richard Daley had requested that the federal government institute a no-fly zone of at least five miles to protect the Sears Tower, the nation's tallest building.

CNN: Chicago gets no-fly zone to protect Sears Tower

Each group can be identified by its costume, particularly the colour of the shirts, while the cummerbund serves to protect the back and is gripped by castellers as they climb up the tower.

UNESCO: Culture