Understanding and improving urban spaces have become an inevitable part of planning cities in the 21st century. Architects and urban designers are constantly trying to identify patterns of growth in various cities, compute solutions for improving the current scenario, and study from the previous anomalies in their urban morphology. 

Slowly and steadily the focus in the urban design sector is shifting from increasing built forms to improving the unbuilt spaces. Designers are gradually beginning to realize how open spaces adjoining buildings are often necessary for retaining activities around them. 

These spaces, the unplanned voids around built forms, are commonly known as – interstitial, residual, or auxiliary spaces – all of which are cognitive in meaning. When these spaces start supporting incidental socio-cultural activities, they become the ‘incidental spaces’ in the urban morphology.

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Moore Street Market, Old Dublin ©TripSavvy.com

What is ‘Incidental?’ | Urban morphology

Every word that we use has a root word and a specific origin. Mostly the present-day meanings of all words stem from their origin or are associated with the meaning of their root word. Thus, before defining ‘Incidental Spaces,’ we must understand the meaning of the word ‘Incidental’ and its origin.

The word ‘Incidental’ is an adjective that is a part of early 17th century English and its origins are from Medieval Latin (incidentals – meaning occurring casually in connection with something else). 

This essentially leads to the present-day meaning of the word: Dictionary defines the adjective ‘Incidental’ as:

  1. Happening as a minor accompaniment to something else.
  2. Happening as a result of (an activity)

Having individually defined ‘Incidental,’ the following meanings can be framed of the term Incidental spaces:

  • A supporting area that caters to the activities happening around it.
  • A space accompanying larger adjacent activities.
  • Spaces that simultaneously form as a part of other activities.

Thus, any space where incidental activities take place will naturally become an incidental space. Also, these open spaces support the closed spaces around them by providing a public interface.

The Built and Unbuilt Spaces

Urban morphology is the study of ‘urban form,’ or in other words the study of the form of human settlements. These forms are a complex composition of the built and the unbuilt. The built spaces refer to the closed spaces whereas the unbuilt refers to the open spaces – it is important to clarify this difference as there may be instances where certain designed open spaces may be ‘built’ interventions but they would still be considered as an unbuilt space. 

The field of urban design found its threshold under the study of the figure-ground diagrams of cities. A figure-ground diagram is a representation technique used to illustrate the built and unbuilt spaces in a city (or in any type of infrastructural masterplan). Built spaces are hatched a solid black, known as “Poché”, whereas the unbuilt spaces are left white.

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The Nolli figure-ground map of Rome ©morphocode.com

This technique was amongst the first tools used for studying urban morphology. It was useful in representing solid-void relationships in urban settings. Depending on the proportion of built vs. unbuilt these diagrams highlighted either the dominance of mass over voids or vice-versa. 

This led to the understanding of how cities with the right proportion of open spaces fostered a healthier atmosphere than the densely built cities indicating the need of including open spaces as a conscious choice in urban planning.

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Houston figure ground map ©Hanshack.com
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Brussels figure ground map ©Hanshack.com

The Urban Morphology of Unbuilt Spaces

As urban design became a mainstream profession, the metropolitan cities all over the world began to be critically analyzed. The form of spaces and their evolution started gaining popularity and that is how the study of the urban morphology of unbuilt spaces came into being. 

The larger umbrella of unbuilt spaces carried under it a wide spectrum of open spaces – broadly categorized into planned and unplanned spaces.

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Planned Urban Open Space ©BibLus-ACCA software
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Unplanned Urban Open Space ©DNA India

The planned open spaces include the public plazas, parks, and recreational hotspots in the city whereas the unplanned open spaces consist of the previously mentioned interstitial, residual, and auxiliary spaces. While the planned spaces are maintained by the governing authorities, the unplanned spaces often turn into useless voids in the urban morphology such as the spaces under the bridges, or the riverside plots. 

Although, often these unplanned spaces pick up spontaneous uses and turn into social or cultural platforms in the city. For example, at a neighborhood level, they serve as gathering space or playgrounds whereas on a city level they house seasonal street markets. In this manner, they allow the citizens to indulge in socio-cultural as well as economical activities throughout the year. 

Recreational activities on an open ground ©81allout.com

The Growth of Unbuilt Spaces into Incidental Spaces | Urban morphology

In a growing city, the unbuilt spaces around the masses are constantly evolving and changing with respect to the various needs of the people- some of these spaces pick up permanent functions from their context and turn into incidental spaces that render different cities different characteristics

These may be the local vegetable markets in a neighborhood, a playground surrounded by residential settlements, or simply a patch of land lined by trees under which people gather for evening talks. All of these activities are spontaneous and are a product of the presence of an empty plot of land. Their spontaneity makes them incidental and therefore, an incidental space is to be understood as an unplanned empty space that supports social or cultural activities daily in a city.

The incidental spaces are often multifunctional spaces that cater to different functions on different occasions – with the changing time as well as the changing seasons. For example, an empty plot used for playing games and for recreational purposes also comes in handy as grounds for large gatherings during the festive and wedding seasons. This proves that despite the common notion that planning every space available in the masterplan would lead to growth it is important that such unplanned spaces be left within each plot of land – which allows and accommodates a wide array of incidental uses throughout the year for people living around it.

Identifying and redeveloping such spaces can certainly lead to the economic growth of the city and it can also empower the city’s existing infrastructure but the redevelopment shouldn’t hamper the multiplicity of the space in terms of the number of functions it supports. Therefore, the urban morphology of incidental spaces is to be left unhindered. In other words, these spaces can allow multiple functions only because of their empty form, and that aspect needs to be retained.

A wise urban intervention need not always involve the use of expensive materials or construction techniques – sometimes it just requires the right planning. 


Raisoni H. (2020) An Introspection of formulation of Urban Voids in highly urbanized Indian Cities. Vietnam.

coreea, c. (2017). housing . In abcd, shelter (pp. 24-70). bombay: sage.

  1. [online] Available at: <https://en.wikipedia.org/wiki/Built_environment.> [Accessed 1 April 2021].

Landman, D. S. (2018). Incidental great public spaces and the role of urban design in South Africa

Ruchita Patel, B. V. (2019). Identification of urban void spaces in an area of vadodaraIdentification of urban void spaces in an area of vadodara. Vadodara: Research Gate.

Saraswat, A. (n.d.). Voids in Architecture- A study of unbuilt spaces. 


Gautami Menon is a final year student at the Institute of Architecture and Planning, Nirma University. As an aspiring architect, she is passionate about expressing design through the written medium. She believes that architectural design is a platform where intellect meets art and her designs are an attempt at justifying the same.