Have you ever heard of the secret lake hidden right beneath the Opéra Garnier in Paris? If you have seen the movie "The Phantom of the Opera", you might have this very wild image of a mysterious and magical lake popping up in your head right now.
Well, guess what! Google went down there and it looks nothing like what we expected. Have a look for yourself here.
Anyway, why is there a lake down there?
Let's go back to 1862 when the Opéra was built. While digging the first foundations, the architect Charles Garnier ran into a little problem. They had hit the Seine and couldn't pump the water away long enough to lay the substructure. After many many many attempts, Charles Garnier came up with a solution: building a cistern thus creating a reservoir of water (very useful in case of imminent fire by the way).
Can I visit?
Unfortunately, the underground of the Opéra Garnier is not open to the public. Only divers from Paris Fire Department go there from time to time in order to train.