"The twentieth century was a time of rapid globalization for advanced art. Artists from a larger number of countries made important contributions than in earlier periods, and they did so in a larger number of places. Many important innovations also diffused more rapidly, and more widely, than in earlier times. The dominance for much of the century of conceptual forms of art, from Cubism and Dada to Pop and Conceptual Art, was largely responsible for the greater speed with which innovations spread: conceptual techniques are communicated more readily, and are generally more versatile in their uses, than experimental methods. There is no longer a single dominant place in the art world, comparable to Paris for the first century of modern art, but it is unlikely that a large number of places will join New York and London as centers of artistic innovation in the future"--National Bureau of Economic Research web site.