What is the largest INDOOR concert?

The largest indoor concert ever held was the Moscow Peace Festival, which took place in the Olympic Stadium in Moscow, Russia, on August 12, 1989. The concert was attended by an estimated 1,500,000 people, and featured performances by some of the biggest names in music at the time, including Billy Joel, Bon Jovi, Mötley Crüe, Scorpions, and Ozzy Osbourne. The concert was broadcast live to over 100 countries, and is considered one of the most significant events in rock music history.