This affects the spatial distribution of the world's cities as the development of these cities results in greater distance between cities. This theory was originally suggested by Christaller and was based on investigations conducted in southern Germany. The major functions of the world's cities have shifted from their former primary roles as centers of international trade, banking and finance to other key functions. These roles include control centers for organizing and influencing the global economy, such as the New York Stock Exchange, advanced telecommunications technologies, and urban development, such as hosting the world's major airports, hosting major sporting events, product markets and a media focus, for example CNN and the CNN effect and New York based news