You can’t define modern civilization without mentioning its cities. These urban settlements vary in culture, size and specialty, with certain areas becoming more significant throughout the development of a region. Historically, the size or population of a settlement was a general indicator of its importance—the bigger city, the more power it yields—however, with the large rural-to-urban migration of the last century, it has become harder to define what makes a city important. There are many types of urban landscapes, and for architects and planners it is vital to efficiently categorize settlement types in order to successfully develop designs and city plans. The following list provides four key definitions that have emerged in the last century.
.jpg?1529231453 "© <a href='https://commons.wikimedia.org/wiki/File:Lujiazui,_Pudong,_Shanghai,_China_-_panoramio_(11).jpg'>Haluk Comertel</a> licensed under <a href='https://creativecommons.org/licenses/by/3.0/deed.en'>CC BY 3.0</a>")
Global City
Tracing back to 1886, its first recorded use described the English port of Liverpool’s involvement in global trade. Now crucial to the modern idea of globalization, ‘global city’ as a term was popularised by Saskia Sassen in 1991 with the cities of London, Tokyo and New York serving as the prime examples. These cities are key locations within the world economy, acting as crucial centres for the global trading of goods and services.
Not strictly dictated by population or size, it is sometimes hard to quantify what makes a global city, but there are several unifying characteristics. Economically, they must serve a variety of international economic services and host the headquarters for several multinational corporations. Socially, it must have a high diversity of cultures, religions, ideologies and languages. There are several cities—like the aforementioned Liverpool—that were once global cities and now are not, and several whose importance is increasing,such as Shanghai.
Metropolis
A metropolis, from the Greek for ‘mother city’, was initially the places from which settlers were sent to discover, and colonize other areas. It has since developed into a descriptive term for large cities that are key centers of national and regional socio-economic activity, sharing many of the same characteristics with a global city.
However, the two terms vary due to the smaller emphasis a metropolis places on international significance. The lower standard of living, development and infrastructure in many metropolises can also impact their status as a global city. As a result, a global city is always a metropolis - but a metropolis isn’t guaranteed to be a global city. Cairo and Lagos reflect the latter.
Megacity
Much less subjective, a ‘megacity’ has been used to describe cities with over a certain amount of inhabitants. The term was first documented by the University of Texas in 1904. Seemingly clear-cut, the definition has some ambiguity, as different organizations suggest different criteria. A city with over 10 million inhabitants is the most widely accepted definition; however, others include urban areas with only 8 million people and also with a population density of 2000 per square kilometer as a megacity.
The first megacity by modern standards was New York, which had surpassed the 10 million population mark by 1936. The early trend saw many of these cities appear in traditionally developed areas—such as Paris, London and Tokyo. However, in recent years there has been a shift. Almost 70% of the current 47 megacities are found in Asia, and this figure is likely to increase in the coming years as the global movement into urban areas continues. Today, the top five most populated cities are Tokyo, Shanghai, Jakarta, Delhi and Seoul.
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Megalopolis
A cluster of well-networked cities is called a megalopolis, a term first used in the early 20th century. These can occur for a variety of reasons since certain areas tend to attract more growth than others. Geography can play a large role in the location of megalopolises, as can good international and regional transport links. The subsequent economic growth of one city can have a positive impact on neighboring locations. One of the first examples of a megalopolis was the north-eastern coast of the USA from Boston to Washington—the Bos-Wash Megalopolis. Much like megacities, however, there are more of these regions developing in Asia than anywhere else right now, such as the Pearl River Delta in China, and the Unified Jakarta-Bandung metro area in Indonesia.
