World's Largest Human Rainbow

On September 18, 2004, over 31,000 students, faculty, staff and alumni of the Polytechnic University of the Philippines broke the record previously held by the Maltese. They used the human rainbow to celebrate the university's centennial, which was from 1904 to 2004, and to highlight the signing of the Declaration of Peace which will be submitted to the United Nations.

This beat the previous effort of 2003, when 11,750 individuals assembled in Floriana, Malta, to break the record. (Link)