Terrassa is an industrial city in the Vallès Occidental, half an hour north of Barcelona by train. Most visitors come for one reason: the Esglésies de Sant Pere, a group of three pre-Romanesque and Romanesque churches that form one of the most important early medieval ensembles in Catalonia. The churches date from the 5th to the 12th century and contain remarkable wall paintings and mosaics.
The city's other claim is its modernista architecture. Terrassa was a textile powerhouse in the late 19th century, and the factory owners commissioned buildings in the Catalan Art Nouveau style. The Masia Freixa, with its parabolic arches in the style of Gaudí, is the standout. The Museu de la Ciència i de la Tècnica de Catalunya, housed in a vast modernista textile mill, traces Catalonia's industrial history. The Casa Alegre de Sagrera preserves one of the most complete bourgeois interiors of the modernisme period.
Terrassa is not a tourist town and makes no effort to be one, but if you are interested in early medieval architecture or Catalan modernisme, it is worth the short train ride from Barcelona.