The Merzbau

Kurt Schwitters, formally known as Kurt Hermann Eduard Karl Julius Schwitters, was a German painter who worked on various elements of what would become installation art.

This took place very gradually; work started in about 1923, the first room was finished in 1933, and Schwitters subsequently extended the Merzbau to other areas of the house until he fled to Norway in early 1937. Most of the house was let to tenants, so that the final extent of the Merzbau was less than is normally assumed. On the evidence of Schwitters’ correspondence, by 1937 it had spread to two rooms of his parents’ apartment on ground floor, the adjoining balcony, the space below the balcony, one or two rooms of the attic and possibly part of the cellar. (via Wikipedia)

Via hcimmi.