Casa Batllo was built in 1904 by the genius architect Antoni Gaudi in the heart of Barcelona on Passeig de Gràcia.  If you are wondering by now who this Antoni Gaudi guy is, the story of his life (and untimely death) are worth a read.  He really had an amazing imagination.  When you walk into the house, you feel like you have walked into a dream.  There are many curved elements, and the house itself is supposed to portray an under the sea feel visible by the choices of colors and shapes.