The term Classical Modernism is useful to summarise the heterogeneous stylistic developments in art in the early 20th century. Although isms can be named for most of the stylistic movements, there are a surprising number of works that cannot be clearly attributed to any of them.
As in the late 19th century, Paris defended its status as the most important art metropolis in Europe. Countless artists trained here or lived for long periods in the city on the Seine. Other important centres, especially of Art Nouveau and the development of abstraction, were Vienna, Munich and Amsterdam.
In the interwar period, cities such as Berlin and New York became equal centres of modernism. With the seizure of power by the National Socialists in Germany and the simultaneous introduction of Socialist Realism in the USSR, the avant-garde currents of the early 20th century were classified as "degenerate", defamed and banned by the authorities.