Casa Batlló is located at number 43 Passeig de Gràcia in Barcelona. The address places Gaudí's celebrated remodel in the Eixample district and within the block popularly known as the Illa de la Discòrdia, or Block of Discord.
Josep Batlló, a wealthy textile industrialist, acquired the building in 1900 and commissioned Gaudí to transform it. Rather than demolishing the existing structure, Gaudí remodeled it between 1904 and 1906, reshaping the façade, interiors, roof, and lightwell. The result is known for its skeletal balconies, scaled surface, colorful ceramic trencadís, and dragon-like roofline.
The neighboring buildings on the same block were designed by other leading Catalan Modernist architects, including Lluís Domènech i Montaner and Josep Puig i Cadafalch. This is why nearby street numbers can cause confusion: Casa Batlló is number 43, while the architectural landmarks beside it have their own distinct addresses. The building forms part of the UNESCO-listed Works of Antoni Gaudí.