An unknown modernist building in Barcelona: The Palau Baró de Quadres
This is not a famous building from the outside, but is definitely worth a visit if you want to discover a super elegant modernist building in la Diagonal avenue (close to Passeig de Gràcia).
Full of decorations using many materials (stone, iron, glass) this small palace was built in 1906 by Puig i Catafalch, one of the most relevant architects of the 19th century together with Antoni Gaudí and Lluís Domenech i Montaner. Indeed, the building is very close to other masterpieces like Casa de les Punxes, Casa Calvet, Casa Batlló or La Pedrera.
The building is considered a National Historical Monument of Artistic Interest. Most of the elements remember the ones in the casa Amatller since the author used to work with similar materials and both buildings were done in the same decade. A masterpiece of wood, stone and glass that is unknown even to the locals.
If you are more interested, you can find more pictures and information here: https://www.llull.cat/monografics/palaubaroquadras/english/index.cfm
This building is not open to be visited as other key attractions of the city. However, tickets can be purchased here for ad-hoc tours: https://www.tiqets.com/en/barcelona-attractions-c66342/tickets-for-palau-baro-de-quadras-guided-tour-p974807/