The Arc de Triomphe is the largest in the world, and where Victor Hugo is buried. It is surrounded by 8 rings of which traffic flows in and out to the 8 directions. I never want to be driving in that mess.
The Opera House inspired The Phantom of the Opera by Gaston Leroux. Nearby is the lavish department store Galeries Lafayette, where all the fashions are overpriced and there is no such thing as a sale.