The Gran Hotel Ciudad de México in Mexico City is decorated in Art Nouveau style. Its crown jewel is the Tiffany stained-glass ceiling in the lobby, installed in 1908 with 150 lights. (Holy crap, that whole ceiling is Tiffany!
The Peacock Room – Castello di Sammezzano in Reggello, Tuscany, Italy. Within an abandoned castle in Tuscany, you can find the Peacock Room, a hidden jewel which features intricate Moorish designs and a breathtaking assortment of patterns and colors