The L'Opera de Paris is located ingame in HKO of course in ... Paris. Of course you knew that! It is another one of the several locked buildings on Sanrio Land, and you can find the key with the help of Melody's Mama. Who is sleeping inside the Opera house? It's Melody's Papa - and he can help you with making new tools. The Palais Garnier also really has many cellars and even still has its underground lake. But it is an artificial lake in reality, taking in the water from the swampy underground, it has to be controlled and pumped out by the fire department periodically.