Paul Klee creates a retreat from the misery of World War I with his etching Luftschlößchen (Little castle in the air). As he noted in his diary in 1915, the year he made this print, and before he had been called up as a soldier, "I have long had this war inside me. That is why inwardly it means nothing to me. And to work my way out of my ruins, I had to fly. And I flew. I remain in this ruined world only in memory, as one occasionally does in retrospect."

The etching makes reference to a number of Klee's memories and interests: the trip to Tunisia he took in spring 1914, crystalline forms, Gothic architecture, the work of French painter Robert Delaunay. The clarity of form he admired in architecture influenced his compositions at this time; he transformed planes and rhythms he saw in the real world to create an imaginary one.