The Nau Gaudí — officially the Cooperativa Obrera Mataronense — is one of the earliest surviving works of Antoni Gaudí, completed in 1883 when he was just 31 years old. The commission came from a workers' cooperative, and Gaudí designed a laundry and shed building using parabolic arches in brick — a structural form he would return to obsessively throughout his career. It is the only surviving industrial building by Gaudí in the world.
The building sits within the larger Can Marfà complex, which now houses the Knitwear Museum. The Nau itself can be visited as part of that complex. Inside, the exposed brick parabolic vaulting is spare and functional compared to Gaudí's later exuberance, but you can clearly see the beginning of the structural logic that would define the Sagrada Família and Park Güell.
Address: Carrer de la Cooperativa, Mataró
Hours: Check with the Museu del Gènere de Punt (Can Marfà), which manages access
Admission: Combined ticket with the Knitwear Museum