Named after Friedrich Engels; the square has had five names.
Friedrich Engels (1820–1895) wrote the Communist Manifesto with Karl Marx in 1847/48. The square, created after the Danube regulation of 1870–1875, was first Kaiser-Josef-Platz, officially Kaiserplatz from 1884 and Engelsplatz from 1920. From 1934 to 1946 it was Pater-Abel-Platz, after the Jesuit preacher Heinrich Abel; it took its present name on 14 May 1946.