A megacity is a very large city, typically with a population of more than 10 million people. The United Nations Department of Economic and Social Affairs in its 2018 "World Urbanization Prospects" report defines megacities as urban agglomerations with over 10 million inhabitants. A University of Bonn report holds that they are "usually defined as metropolitan areas with a total population of 10 million or more people". Elsewhere in other sources, from five to eight million is considered the minimum threshold, along with a population density of at least 2,000 per square kilometre. The terms conurbation, metropolis, and metroplex are also applied to the latter.
A metropolitan area or metro is a region consisting of a densely populated urban agglomeration and its surrounding territories which share industries, commercial areas, transport network, infrastructures and housing. A metropolitan area usually comprises multiple principal cities, jurisdictions and municipalities: neighborhoods, townships, boroughs, cities, towns, exurbs, suburbs, counties, districts and even states and nations in areas like the eurodistricts. As social, economic and political institutions have changed, metropolitan areas have become key economic and political regions.
A conurbation is a region comprising a number of metropolises, cities, large towns, and other urban areas which, through population growth and physical expansion, have merged to form one continuous urban or industrially developed area. In most cases, a conurbation is a polycentric urbanised area in which transportation has developed to link areas. They create a single urban labour market or travel to work area.
Greater Buenos Aires, also known as the Buenos Aires Metropolitan Area, refers to the urban agglomeration comprising the Autonomous City of Buenos Aires and the adjacent 24 partidos (districts) in the Province of Buenos Aires. Thus, it does not constitute a single administrative unit. The conurbation spreads south, west and north of Buenos Aires city. To the east, the River Plate serves as a natural boundary.
An aire urbaine is an INSEE statistical concept describing a core of urban development and the extent of its commuter activity. It was replaced by the concept "functional area", which uses the same definition as Eurostat's functional urban areas, in 2020.
An urban area is a human settlement with a high population density and an infrastructure of built environment. This is the core of a metropolitan statistical area in the United States, if it contains a population of more than 50,000.
A city proper is the geographical area contained within city limits. The term proper is not exclusive to cities; it can describe the geographical area within the boundaries of any given locality. The United Nations defines the term as "... the single political jurisdiction which contains the historical city centre."
The Flemish Diamond is the Flemish reference to a network of four metropolitan areas in Belgium, three of which are in the central provinces of Flanders, together with the Brussels-Capital Region. It consists of four agglomerations which form the four corners of an abstract diamond shape: Brussels, Ghent, Antwerp and Leuven.
The Blue Banana, also known as the European Megalopolis or the Liverpool–Milan Axis, is a discontinuous corridor of urbanization in Western and Central Europe, with a population of around 100 million. The conceptualisation of the area as a "Blue Banana" was developed in 1989 by RECLUS, a group of French geographers managed by Roger Brunet.
A metropolis is a large city or conurbation which is a significant economic, political, and cultural area for a country or region, and an important hub for regional or international connections, commerce, and communications.
The Katowice urban area, also known as the Upper Silesian urban area, is an urban area/conurbation in southern Poland, centered on Katowice. It is located in the Silesian Voivodeship. The Katowice urban area is the largest urban area in Poland and 22nd largest urban area in the European Union. According to Demographia, its population is 1,903,000.
A 2001 ESPIN metropolitan area was defined as consisting of an urban area, conurbation or agglomeration, together with the surrounding area to which it was closely economically and socially integrated through commuting.
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