Catenary arches on the top floor of Casa Batlló - a building designed by Gaudí in the Eixample district of Barcelona, Spain. The local name for the building is Casa dels ossos (House of Bones), and indeed it does have a visceral, skeletal organic quality. It was originally designed for a middle-class family and situated in a prosperous district of Barcelona. The building looks very remarkable — like everything Gaudí designed, only identifiable as Modernisme or Art Nouveau in the broadest sense. The ground floor, in particular, is rather astonishing with tracery, irregular oval windows and flowing sculpted stone work. It seems that the goal of the designer was to avoid straight lines completely. Much of the façade is decorated with a mosaic made of broken ceramic tiles (trencadís) that starts in shades of golden orange moving into greenish blues. The roof is arched and was likened to the back of a dragon or dinosaur. A common theory about the building is that the rounded feature to the left of centre, terminating at the top in a turret and cross, represents the sword of Saint George (patron saint of Catalonia), which has been plunged into the back of the dragon.