Urban Structures and City Models
Metropolitan Area
An urban extension surrounding a large city encompasses different, independent municipalities with significant economic ties. Key characteristics of a metropolitan area include a central city of substantial size and functional complexity, commuter migration from satellite towns, geographic contiguity between municipalities, and a developed transport system connecting the central city and its surrounding area.
The internal structure of a metropolitan area typically comprises three sectors: the inner city (old town and expansions), the sub-metropolitan area (peripheral neighborhoods with a mix of residential, industrial, and service functions like universities and hospitals), and the suburban area at the outer periphery.
Dormitory Town
A dormitory town primarily serves as a residential area for people who commute daily to work in nearby areas. These towns emerge near large cities experiencing rapid industrial development and growth. Besides dormitory towns, other urban forms arise, including residential towns, congested cities, and recreational or tourist destinations. Initially, they may appear as mere suburbs with limited functionality, but they gradually evolve into autonomous urban cells gravitating around the core city.
Garden City
The garden city concept attempts to blend the advantages of rural and urban living. Originating in late nineteenth-century England, this model involves establishing small residential towns with ample green spaces, separated by a few kilometers from a medium-sized town and well-connected by train and road. This system has been implemented in England, around London, and in upscale neighborhoods of other capital cities (e.g., La Moraleja in Madrid).
Linear City
Designed by Arturo Soria y Mata, the linear city is a garden city with linear transportation. The concept proposed connecting two existing cities with a long urban strip, approximately 500 meters wide, featuring railways at different levels and speeds. All urban services (water, sewage, etc.) would run underground along this route. Community buildings, shops, and public services would be located at regular intervals, alongside single-family houses with orchards and gardens. A 5 km stretch was built in Madrid based on this project, although it has since been largely transformed.
Satellite City
A satellite city is a small or medium-sized city with a primarily residential character, located near a larger city on which it is functionally dependent.
Conurbation
A conurbation occurs when two independent cities physically merge due to growth, while maintaining their autonomy. This phenomenon is typical of large metropolitan areas. Several examples exist in Spain, particularly along the coast due to tourism-driven urban growth, such as Benalmádena and Torremolinos in Malaga. Other examples include Tarragona and Vilaseca, or San Sebastián de los Reyes and Alcobendas in Madrid.
Megalopolis
A megalopolis results from the continuous growth of a large city into a massive agglomeration. The term describes the union of several metropolitan areas, collectively reaching a minimum population of 20 million. In this strict sense, megalopolises do not exist in Spain, but examples can be found in Japan (Tokyo-Yokohama).
Orthogonal Plan
This urban form features well-planned, straight, wide streets intersecting at right angles, creating square blocks. Also known as a “grid” or “checkerboard” plan, it was first used in Roman cities and later appeared in planned cities (e.g., many South American cities) or in nineteenth-century expansion neighborhoods built on vacant land (e.g., Eixample in Barcelona, Salamanca district of Madrid).
Radiocentric Plan
This model revolves around a central space (square, cathedral, city hall), with streets radiating outwards to the periphery, intersected by concentric roads. The city center, the historical and monumental nucleus, is emphasized in this layout. This system facilitates communication between the center and periphery. Favored by Renaissance urban utopians (Sforzinda), this model remains widely accepted.
Irregular Plan
Characterized by an anarchic arrangement of narrow, often dead-end streets, this layout is typical of historical “old cities” with Arab origins (e.g., Seville, Toledo). It was also common in many European cities during the Middle Ages. Few cities today are entirely built with this plan.
Suburb
In Spain, “suburb” can refer to slums or heavily degraded urban areas. However, it generally denotes the peripheral space where the city expands and meets the surrounding countryside—a zone of convergence between urban and rural environments. Suburbs can vary greatly in appearance, from small single-family homes to large apartment buildings, and often include slums in major cities like Madrid, Barcelona, and Bilbao.
Social Housing
Social housing refers to construction projects where housing is subsidized and supported by public authorities, enabling access to the market at low prices and under special acquisition conditions. Intended for disadvantaged social groups, it has sometimes been used to absorb shantytowns, as in the case of Unidades Vecinales de Absorción (UVAs). This phenomenon was particularly prominent in the 1980s when the public sector intervened to curb rising property market prices.