Hundertwasser's comment on the work

As a kind of pre-philosophy of my later architectural activities, I was fascinated by the keystones which held the Roman/Romanesque arches together. In Vienna, in particular, these keystones were changed into plaster ornaments above the windows. Almost like when you say, "Without a necktie you're not a gentleman", or "Without a keystone that's not a window". Also, it is a dream-like oddity that a keystone-window looks very much like a rubber hot-water bottle with a funnel on it. (from: Hundertwasser 1928-2000, Catalogue Raisonné, Vol. 2, Taschen, Cologne, 2002, p. 465)