The walk traces the great avenue of Passeig de Gràcia and the concentrated creativity of Catalan Modernisme, revealing why this stretch became the showcase for Barcelona’s most inventive architects. Beginning with an account of the Eixample and Ildefons Cerdà’s grid and chamfered corners, the guide explains how urban planning shaped light, air and the social ambitions of the late 19th century. The route reaches the renowned Illa de la Discòrdia, where the juxtaposition of Casa Lleó Morera, Casa Amatller and Casa Batlló offers a vivid lesson in stylistic difference and architectural narrative. Close attention is given to Casa Batlló’s remodel: the masking balconies, sinuous columns, broken-tile surface and the roof-form that suggests a dragon’s back. Further along, the tour examines Casa Milà (La Pedrera), its seemingly irregular stone façade, wrought-iron balconies and the structural innovations that freed interior layouts from load-bearing walls. Through close-looking and contextual stories, the guide helps participants learn to read façades, recognise materials and motifs, and understand how Modernisme related to Barcelona’s social and economic life.