Illusion was a song that was played at the Eurovision contest held in what most populous city in Russia?
Illusion (Krassimir Avramov song):  The song represented Bulgaria at the Eurovision Song Contest 2009 in Moscow, Russia. Moscow: Moscow ( or ; Russian: Москва́ , "Moskva"; ] ) is the capital and most populous city of Russia, with 13.2 million residents within the city limits and 17.1 million within the urban area.
Moscow