Casa Navàs is one of the best examples of Catalan Art Nouveau (Modernisme) in Europe because of its singularity. Built by the architect Lluís Domènech i Montaner and decorator Gaspar Homar between 1901 and 1908, the house has maintained all its original rooms and furniture and is the only Modernista building in Europe that has been preserved in its original state.

The building was commissioned by Joaquim Navàs, a rich textile merchant, at a time when Reus was in full swing. Navàs and his wife, Pepa Blasco, asked Domènech i Montaner to build a combination house and store on one of the corners of Plaça del Mercadal in Reus. The commission had an almost unlimited budget and therefore led to one of this Barcelona architect's most opulent works.

As the second capital of Catalonia, Reus was one of the most heavily bombed cities during the Spanish Civil War and Casa Navàs also suffered because of this. It lost its tower and much of its roof to a bomb in 1938 and even several of its second-storey spaces were destroyed. Most of the rooms were restored by the same owners after the war had ended; nonetheless, the upper section of the façade still displays some major imperfections, such as its large upper finish and corner tower that used to give the building an elegant, slim look.

The most comprehensive, fanciful and splendid interior of Modernisme is hidden behind the external aspect of today's damaged building. Entering the house is akin to entering a large artificial garden filled with flourishes, highlighted by stained glass windows of more than two hundred square metres among skylights, partitions, doors and windows. In addition, nearly all of its decorative elements, such as furniture, embroidered upholstery, ceramics, paintings, silk fabrics, lamps and blinds, have been preserved. Domènech i Montaner surrounded himself with the best artisans of the time to complete all these pieces, such as Gaspar Homar, Lluís Bru, Antoni Rigalt, Jeroni Granell, Eusebi Arnau, Pujol and Bausis and Hipòlit Montseny.