At the Yokohama International Triennale of Contemporary Art, their response to September 11 was to build Bird Cage, a five-metre-high cone constructed from hemp rope. Every day for ten weeks the cone released a balloon which, after floating to a height of ten kilometres, burst and released a balsa wood bird to carry a ‘message of hope’ on the four winds. Bird Cage, along with Yoko Ono’s Freight Train, was widely regarded as a highlight of the show.