Cities as Political Centers
While ancient cities may have arisen organically as trading centers, preindustrial cities evolved to become well defined political units, like today's states. During the European Middle Ages, a town was as much a political entity as a collection of houses. However, particular political forms varied. In continental Europe, some cities had their own legislatures. In the Holy Roman Empire, some cities had no other lord than the emperor. In Italy, medieval communes had a state-like power. In exceptional cases like Venice, Genoa, or Lübeck, cities themselves became powerful states, sometimes taking surrounding areas under their control or establishing extensive maritime empires. Similar phenomena existed elsewhere, as in the case of Sakai, which enjoyed a considerable autonomy in late medieval Japan.
For people during the medieval era, cities offered a newfound freedom from rural obligations. City residence brought freedom from customary rural obligations to lord and community (hence the German saying, "Stadtluft macht frei," which means "City air makes you free"). Often, cities were governed by their own laws, separate from the rule of lords of the surrounding area.
Not all cities grew to become major urban centers. Those that did often benefited from trade routes—in the early modern era, larger capital cities benefited from new trade routes and grew even larger. While the city-states, or poleis, of the Mediterranean and Baltic Sea languished from the 16th century, Europe's larger capitals benefited from the growth of commerce following the emergence of an Atlantic trade. By the early 19th century, London had become the largest city in the world with a population of over a million, while Paris rivaled the well-developed regional capital cities of Baghdad, Beijing, Istanbul, and Kyoto. But most towns remained far smaller places—in 1500 only about two dozen places in the world contained more than 100,000 inhabitants. As late as 1700 there were fewer than 40, a figure which would rise thereafter to 300 in 1900. A small city of the early modern period might have contained as few as 10,000 inhabitants.