Rhine-Ruhr transportation from any point in the Rhine Ruhr area to the venue and return. Duisburg Port (Duisport) and Dortmund Port are large industrial inland ports and serve as hubs along the Rhine and the German inland water transport system. The region is host to numerous large events, comprising fun fairs and cultural events like the Cologne and Düsseldorf carnivals (carnival is however a public event in almost all cities and towns of the area), the Cologne Comedy Festival, Ruhrfestspiele Recklinghausen, and the RuhrTriennale, as well as gamescom and other trade fairs at koelnmesse—Cologne Trade Fair and Messe Düsseldorf; and Essen
Ruhr breaks between the individual city boroughs. Thus the Ruhr is described as a polycentric urban area, which shares a similar history of urban and economic development. Because of its history, the Ruhr is structured differently from monocentric urban regions such as Berlin and London, which developed through the rapid merger of smaller towns and villages with a growing central city. Instead, the individual city boroughs and urban districts of the Ruhr grew independently of one another during the Industrial Revolution. The population density of the central Ruhr is about 2,100 inhabitants per square kilometre (about 5,400 per square mile)—low compared