Understanding Urban Settlements and City Hierarchies

1. What Is a City?

There is no single factor that explains whether a place can be described as a city or not.

2. Rural and Urban Settlements

There are essentially two types of human settlement:

• Rural settlement: Large areas with population densities below 150 inhabitants/km². These are small settlements that are either dispersed or concentrated in villages. Agricultural and livestock farming activities are usually predominant.
• Urban settlements: Less extensive areas, but with population densities greater than 150 inhabitants/km². Larger settlements are normally known as cities or towns, characterized by intense movements of people.

3. Urban Functions and Layouts

Functions: The main functions include residential, industrial, political-administrative, cultural, financial, and tourism.

Urban Layout Patterns

• Irregular urban layout: Irregular shape, made up of narrow, winding streets. It is found in cities with a historic center (e.g., Muslim cities and medieval centers of many European cities like Toledo).
• Orthogonal grid layout: Square or rectangular. Its origin dates back to Greek and Roman cities. It features a fairly regular grid in which streets usually run at right angles to each other, often used in 19th and 20th-century expansion zones.
• Radial or concentric urban pattern: This organizes the city around an important central point, like a spider’s web. Streets provide easy access between the outskirts of the city and the center.

4. The Classification and Hierarchy of Cities

Urbanization has intensified significantly in recent decades, leading cities to increase their territory and areas of influence.

• Conurbation: Nearby cities of similar importance expand and merge together.
• Metropolitan area: This occurs when a big city merges with other smaller cities and towns.
• Urban region: This consists of several scattered cities and towns that are close together.
• Megacity or megalopolis: A succession of conurbations and metropolitan areas linked by infrastructure systems that facilitate the mobility of people, goods, and information.
• Global Cities: Cities with the power to make economic and political decisions that affect the world. International political and economic institutions are based here.
• National Cities: State capitals or other large cities of a country with considerable international influence.
• Regional cities: Medium-sized cities with fewer urban functions, influenced by the national city.

The Dynamic Role of Big Cities

There are few global cities that occupy the top of the urban hierarchy. Their characteristics include being centers of major political and commercial decisions that affect the lives of millions of people.