Honeycomb (1969)

This film is not just one of the great results of Saura and Geraldine Chaplin creative and marital union, but one of the rare movies where the environment, the house here, takes the main role.
The huge, abstract, pre-minimalist concrete house (by Spanish architect Carvajal) transforms itself during the whole film running, setting the path to the main characters paranoia. The images that Saura produces are enigmatic, surrealist, funny, and in a strange way therapeutic, and they are deeply rooted in Spanish cubism and surrealism. It is probably one of the most contemporary and interesting film by the director, not recognized, yes, but a great unexpected value anyway.