Constant himself gave this work the title Visionaire stad (Visionary city) but when the work was exhibited at the Biennale in Venice in 1966 the work was titled Constructie met ladders.

Constant exchanged the painting, Kat, 1949, with Tajiri's sculpture, Circus. Following documentation of the works in catalogs the exchange took place before 1962. Circus is documented in Cobra, Journaal van de Nederlandse musea voor moderne kunst in 1962 as belonging to the collection of Constant.*

In the 1980 exhibition catalog nr. 39 of Constant. Schilderijen 1940-1980 the date on the painting Kat is "1950" not "1949". The photo in the catalog was taken by Victor Nieuwenhuys, Constant's son. In the 1965 catalog nr. 30 of Constant the painting Kat is dated "1950", coll. S. Tajiri, Baarlo, L. Restorer Marjan de Visser recognised Constant's hand in the date change when she restored the painting in 2015. We have no documentation on why the date was changed and when.

*Source: Troels Andersen, Christian Dotremont, Gerrit Kouwenaar, J. Martinet, J. Eijkelboom en Wim Beeren, Cobra, Journaal van de Nederlandse musea voor moderne kunst, januari/februari 1962 – serie 7 no 7/8, afb. p. 188 [Tajiri, Circus 1952, Coll. C. Nieuwenhuys, Amsterdam].