Castle of the Three Dragons

Built for the 1888 Universal Exposition as a café-restaurant, the Castell dels Tres Dragons was one of Lluís Domènech i Montaner's earliest major works and is considered a foundational building of Catalan Modernisme, combining exposed brick, medieval castle-like turrets, and industrial ironwork years before Gaudí's more famous designs. It later housed Barcelona's Museum of Zoology for decades and has undergone periods of renovation, which reviewers note has sometimes limited interior access.

Regardless, it remains a striking structure to encounter while walking through Parc de la Ciutadella, with the park's fountain and gardens nearby offering a pleasant place to rest. It appeals most to those interested in the architectural roots of Modernisme rather than a specific collection inside.