Where
When
Why - two reasons: United Nations' Alliance of Civilizations (UNAOC) Forum's yearly summit and inauguration of the Ampitheatron at the Katara Cultural village. This one.
Who - Vangelis, who composed new music for this event, Angela Gheorghiu, Roberto Alagna, Qatar's Philharmonic Orchestra, the Russian State Academic Choir, the Qatar Philharmonic Orchestra's children choir
