The Opera Garnier has an underground lake that inspired the Phantom’s lair in 'Phantom of the Opera'. Emptying the underground cistern would cause the Opera to collapse!

Box number 5 at the Opera Garnier was supposedly privately reserved by the Phantom every night in real life and is today the first to sell out.

Banks near the Opera Garnier would stay open late when there was a performance as wealthy opera-goers who stored their expensive jewelry would take them out just for this occasion.