The local name for the building is Casa dels ossos (House of Bones), and indeed it does have a visceral, skeletal organic quality.

Close up of Casa Batllo chimney
Casa Batllo’s roof has been compared to a reptilian creature, the backbone of a gigantic dinosaur, the dragon killed by St. George (Sant Jordi being the patron saint of Catalan).

Casa Batllo roof
It seems that the goal of the designer was to avoid straight lines completely. Much of the facade is decorated with a mosaic made of broken ceramic tiles that starts in shades of golden orange moving into greenish blues.

Casa Batllo arched roof

Casa Batllo building, Barcelona

Casa Batllo arched roof and complex chimney detailing
From the balconies resembling the bones of animals to the scale like surface of the front facade, the building is a tour de force of an artist reaching the peak of his powers. At night the floodlit facade has an iridescence like the scales of a fish. This polychromic finish is known as trencadís.

Casa Batllo, Barcelona in HDR
The enlarged windows on the first floor gave it another nickname, ‘House of Yawns’.

Casa Batllo window, Barcelona

Window detail of Caso Batllo building

Casa Batllo Interior Design
Inside Caso Batllo

Inside Caso Batllo

Inside Caso Batllo

Caso Batllo: Spiral Design

Caso Batllo: Spiral Design

Caso Batllo lobby