The Passeig de Gràcia, the main thoroughfare of the Eixample district, was built in the second half of the nineteenth century. Between late 1904 and early 1906, Gaudí was commissioned by industrialist Josep Batlló i Casanovas to build there what is undoubtedly considered one of his major master works. Although it may seem so at first sight, Casa Batlló was not new but a reform of an existing building. Gaudí transformed its appearance radically, renovating the interior and façades with such original shapes and colours that from the moment the work was completed the building became an icon in the Barcelona urban landscape.
The façade of Casa Batlló, an outburst of Gaudian fantasy, has given rise to many interpretations. Some have compared its curved forms with the waves of the sea, and the ceramic and glass ornamentation that gives it such colour with marine fauna and alga. Others see its cladding as an allusion to confetti at Carnival time, an idea reinforced by the fantasy shapes of the cast iron grilles on the balconies that resemble Venetian masks. The same balconies have also been compared with skulls, and like the surprising bone-shaped columns on the first-floor tribune, are thought to represent the victims of the dragon in the legend of Sant Jordi. The dragon would be symbolised by the roof covered with scale-like ceramics from which rises a tower crowned by a four-armed cross, identified with the sword of Sant Jordi that killed the beast.
Interpretations apart, the main façade of Casa Batlló is a compendium of structural inventions and forms repeated throughout the building: the strange mushroom-shaped chimneys, the back façade with trencadis in natural and geometric shapes, and the beautiful inner courtyard where Gaudí graded the size of the windows and the colour of the ceramic coating progressively to help spread light throughout the interior.