Casa Batlló, one of Europe's most eccentric residential structures, is a marvel of Gaudí's imagination. Built between 1904 and 1906, the building's façade is a playful showcase of his creativity, and its unconventional design, inspired by the seaside, features multiple innovative experiments in light and form—deviating from conventional straight lines. Situated in a city renowned for its architectural extravagance, Casa Batlló is a stunningly beautiful testament to Gaudí's brilliance.