Main article: History of the city
Further information: Urban history, Historical urban community sizes, and List of largest cities throughout history

An arch from the ancient Sumerian city Ur, which flourished in the third millennium BC, can be seen at present-day Tell el-Mukayyar in Iraq

Mohenjo-daro, a city of the Indus Valley Civilization in Pakistan, which was rebuilt six or more times, using bricks of standard size, and adhering to the same grid layout—also in the third millennium BC.

This aerial view of what was once downtown Teotihuacan shows the Pyramid of the Sun, Pyramid of the Moon, and the processional avenue serving as the spine of the city's street system.
Cities, characterized by population density, symbolic function, and urban planning, have existed for thousands of years. In the conventional view, civilization and the city both followed from the development of agriculture, which enabled production of surplus food, and thus a social division of labour (with concomitant social stratification) and trade.[41][42] Early cities often featured granaries, sometimes within a temple.[43] A minority viewpoint considers that cities may have arisen without agriculture, due to alternative means of subsistence (fishing),[44] to use as communal seasonal shelters,[45] to their value as bases for defensive and offensive military organization,[46][47] or to their inherent economic function.[48][49][50] Cities played a crucial role in the establishment of political power over an area, and ancient leaders such as Alexander the Great founded and created them with zeal.[51]
Ancient times[edit]
Further information: Cities of the Ancient Near East, Polis, City-state, and Late Antiquity § Cities
Jericho and Çatalhöyük, dated to the eighth millennium BC, are among the earliest proto-cities known to archaeologists.[45][52]
In the fourth and third millennium BC, complex civilizations flourished in the river valleys of Mesopotamia, India, China, and Egypt. Excavations in these areas have found the ruins of cities geared variously towards trade, politics, or religion. Some had large, dense populations, but others carried out urban activities in the realms of politics or religion without having large associated populations. Among the early Old World cities, Mohenjo-daro of the Indus Valley Civilization in present-day Pakistan, existing from about 2600 BC, was one of the largest, with a population of 50,000 or more and a sophisticated sanitation system.[53] China's planned cities were constructed according to sacred principles to act as celestial microcosms.[54] The Ancient Egyptian cities known physically by archaeologists are not extensive.[19] They include (known by their Arab names) El Lahun, a workers' town associated with the pyramid of Senusret II, and the religious city Amarna built by Akhenaten and abandoned. These sites appear planned in a highly regimented and stratified fashion, with a minimalistic grid of rooms for the workers and increasingly more elaborate housing available for higher classes.[55]
In Mesopotamia, the civilization of Sumer, followed by Assyria and Babylon, gave rise to numerous cities, governed by kings and fostering multiple languages written in cuneiform.[56] The Phoenician trading empire, flourishing around the turn of the first millennium BC, encompassed numerous cities extending from Tyre, Cydon, and Byblos to Carthage and Cádiz.
In the following centuries, independent city-states of Greece developed the polis, an association of male landowning citizens who collectively constituted the city.[57] The agora, meaning "gathering place" or "assembly", was the center of athletic, artistic, spiritual and political life of the polis.[58] Rome's rise to power brought its population to one million. Under the authority of its empire, Rome transformed and founded many cities (coloniae), and with them brought its principles of urban architecture, design, and society.[59]
In the ancient Americas, early urban traditions developed in the Andes and Mesoamerica. In the Andes, the first urban centers developed in the Norte Chico civilization, Chavin and Moche cultures, followed by major cities in the Huari, Chimu and Inca cultures. The Norte Chico civilization included as many as 30 major population centers in what is now the Norte Chico region of north-central coastal Peru. It is the oldest known civilization in the Americas, flourishing between the 30th century BC and the 18th century BC.[60] Mesoamerica saw the rise of early urbanism in several cultural regions, beginning with the Olmec and spreading to the Preclassic Maya, the Zapotec of Oaxaca, and Teotihuacan in central Mexico. Later cultures such as the Aztec drew on these earlier urban traditions.
Jenné-Jeno, located in present-day Mali and dating to the third century BC, lacked monumental architecture and a distinctive elite social class—but nevertheless had specialized production and relations with a hinterland.[61] Pre-Arabic trade contacts probably existed between Jenné-Jeno and North Africa.[62] Other early urban centers in sub-Saharan Africa, dated to around 500 AD, include Awdaghust, Kumbi-Saleh the ancient capital of Ghana, and Maranda a center located on a trade route between Egypt and Gao.[63]
In the first millennium AD, Angkor in the Khmer Empire grew into one of the most extensive cities in the world[64][65] and may have supported up to one million people.[66]
Middle Ages[edit]

Imperial Free Cities in the Holy Roman Empire 1648

This map of Haarlem, the Netherlands, created around 1550, shows the city completely surrounded by a city wall and defensive canal, with its square shape inspired by Jerusalem.
In the remnants of the Roman Empire, cities of late antiquity gained independence but soon lost population and importance. The locus of power in the West shifted to Constantinople and to the ascendant Islamic civilization with its major cities Baghdad, Cairo, and Córdoba.[67] From the 9th through the end of the 12th century, Constantinople, capital of the Byzantine Empire, was the largest and wealthiest city in Europe, with a population approaching 1 million.[68][69] The Ottoman Empire gradually gained control over many cities in the Mediterranean area, including Constantinople in 1453.
In the Holy Roman Empire, beginning in the 12th. century, free imperial cities such as Nuremberg, Strasbourg, Frankfurt, Zurich, Nijmegen became a privileged elite among towns having won self-governance from their local lay or secular lord or having been granted self-governanace by the emperor and being placed under his immediate protection. By 1480, these cities, as far as still part of the empire, became part of the Imperial Estates governing the empire with the emperor through the Imperial Diet.[70]
By the thirteenth and fourteenth centuries, some cities become powerful states, taking surrounding areas under their control or establishing extensive maritime empires. In Italy medieval communes developed into city-states including the Republic of Venice and the Republic of Genoa. In Northern Europe, cities including Lübeck and Bruges formed the Hanseatic League for collective defense and commerce. Their power was later challenged and eclipsed by the Dutch commercial cities of Ghent, Ypres, and Amsterdam.[71] Similar phenomena existed elsewhere, as in the case of Sakai, which enjoyed a considerable autonomy in late medieval Japan.
Early modern[edit]
In the West, nation-states became the dominant unit of political organization following the Peace of Westphalia in the seventeenth century.[72][73] Western Europe's larger capitals (London and Paris) benefited from the growth of commerce following the emergence of an Atlantic trade. However, most towns remained small.
During the Spanish colonization of the Americas the old Roman city concept was extensively used. Cities were founded in the middle of the newly conquered territories, and were bound to several laws regarding administration, finances and urbanism.
Industrial age[edit]
The growth of modern industry from the late 18th century onward led to massive urbanization and the rise of new great cities, first in Europe and then in other regions, as new opportunities brought huge numbers of migrants from rural communities into urban areas.

Diorama of old Gyumri, Armenia with the Holy Saviour's Church (1859–1873)

Small city Gyöngyös in Hungary in 1938.
England led the way as London became the capital of a world empire and cities across the country grew in locations strategic for manufacturing.[74] In the United States from 1860 to 1910, the introduction of railroads reduced transportation costs, and large manufacturing centers began to emerge, fueling migration from rural to city areas.
Industrialized cities became deadly places to live, due to health problems resulting from overcrowding, occupational hazards of industry, contaminated water and air, poor sanitation, and communicable diseases such as typhoid and cholera. Factories and slums emerged as regular features of the urban landscape.[75]
Post-industrial age[edit]
In the second half of the twentieth century, deindustrialization (or "economic restructuring") in the West led to poverty, homelessness, and urban decay in formerly prosperous cities. America's "Steel Belt" became a "Rust Belt" and cities such as Detroit, Michigan, and Gary, Indiana began to shrink, contrary to the global trend of massive urban expansion.[76] Such cities have shifted with varying success into the service economy and public-private partnerships, with concomitant gentrification, uneven revitalization efforts, and selective cultural development.[77] Under the Great Leap Forward and subsequent five-year plans continuing today, the People's Republic of China has undergone concomitant urbanization and industrialization and to become the world's leading manufacturer.[78][79]
Amidst these economic changes, high technology and instantaneous telecommunication enable select cities to become centers of the knowledge economy.[80][81][82] A new smart city paradigm, supported by institutions such as the RAND Corporation and IBM, is bringing computerized surveillance, data analysis, and governance to bear on cities and city-dwellers.[83] Some companies are building brand new masterplanned cities from scratch on greenfield sites.