Notting Hill Carnival (London, UK)

Notting Hill Carnival is Europe's largest street festival, drawing 2 million revelers over two days—a staggering 30% more visitors than #3 Day of the Dead Parade. The Afro-Caribbean celebration features towering sound systems, mas bands, and jerk chicken that perfumes entire postcodes. With 40,000 volunteers and 300+ food stalls, it generates £120 million for London's economy, outperforming #2 La Mercè by £50 million in economic impact.