Interstitial spaces are the city’s secret heroes – they sneak between houses, under bridges, along railroad tracks and into gaps that no one ever planned. What many consider to be wild no man’s land turns out, on closer inspection, to be a laboratory for urban innovation, social movement and ecological diversity. Anyone who sees the “unplanned” as nothing more than a residual area is missing out on the most exciting stories of urban development and the greatest opportunities for transformation.
- Definition and significance of urban in-between spaces in the context of contemporary urban planning
- Historical development and cultural perception of the “unplanned” in the city
- Mechanisms and potentials of transformation: from brownfields to creative uses
- Strategies and challenges in the integration of interstitial spaces in sustainable urban development
- Case studies and best practice examples from Germany, Austria and Switzerland
- The role of participation, interim use and temporary architecture
- Ecological, social and economic values of unplanned spaces
- Risks of commercialization and displacement of informal uses
- Perspectives for future planning approaches and the understanding of urbanity
What are intermediate spaces? The unplanned as a resource for the city
In traditional urban planning, in-between spaces were long regarded as “white spots” on the plan, as remnants of supposedly incomplete planning or as evidence of stagnation and disinterest. But this view falls far short of the mark. Intermediate spaces are those areas that cannot be directly used for a specific purpose: Railroad embankments, overgrown plots of land, forgotten backyards, wasteland, residual areas along traffic axes and unused building ensembles. They are often the result of economic shifts, structural change or simply planning errors. But it is precisely in their indeterminacy and openness that their greatest potential lies.
Intermediate spaces are spaces of possibility. They offer space for experiments, for temporary uses, for spontaneous interventions and for social and ecological innovations. While planned parks and squares structure everyday urban life, interstitial spaces invite people to try things out, linger and change. They are the stage for processes that defy control: Wild growth, graffiti, guerrilla gardening, neighborhood festivals or urban art often emerge where urban planning does not look – or does not want to look.
However, it would be a mistake to regard in-between spaces as mere “empty spaces”. They are not just what remains when the city is “finished”. Rather, they are elementary components of the urban fabric – dynamic zones where urban society and nature meet. They make it possible to try out new forms of appropriation and coexistence, beyond the logic of investors and the pressure to exploit. Those who understand the spaces in between see the city as an organism, not as a machine.
The term “unplanned” does not have a negative connotation. Rather, it refers to a quality that is often lost in the rigid corset of classic urban planning: flexibility, openness, unpredictability. It is precisely the unplanned places that give the city the vitality and diversity that make it so fascinating. They challenge planners to think in terms of processes rather than products – and to embark on the urban adventure.
The appreciation of in-between spaces is by no means a marginal phenomenon. International experts are discussing them as key resources for resilient, sustainable and inclusive urban development. Interstitial spaces are not the opposite of planning, but a necessary complement to it. They are the buffer zones against monoculture, over-development and displacement – and offer a stage for the “unexpected”.
Historical and cultural perspectives: Interstitial spaces through the ages
The history of in-between spaces is as old as the city itself – and at least as exciting. Even in ancient Rome, there were wastelands between the insulae that served as meeting places, markets or gardens. In the Middle Ages, these were the “allmenden” and “Anger”, communal open spaces on the edge of settlements. But with modernism and the functionalist urban planning of the 20th century, intermediate spaces were increasingly seen as deficiencies, as disruptive factors in the grid of the perfect city.
The Athens Charter and the ideas of the car-friendly city focused on clear zoning and the separation of living, working and recreation. Anything that did not fit the pattern was eliminated or ignored as “disorder”. It was only with the criticism of this functionalist logic – by authors such as Jane Jacobs and Jan Gehl – that the “Spaces in Between” came back into the focus of urban research. Jacobs’ famous sentence “Cities have the capability of providing something for everybody, only because, and only when, they are created by everybody” puts it in a nutshell: the quality of the city often lies in the unplanned, in the interplay of the many small open spaces.
The cultural perception of unplanned spaces fluctuates between fascination and rejection. While vacant lots in Berlin, Vienna or Zurich are celebrated as hotspots of the creative scene, elsewhere they are seen as eyesores or spaces of fear. The media and pop culture also play their part: In-between spaces are sometimes romanticized as “lost places”, sometimes stigmatized as “problem zones”. This ambivalence reflects the way society deals with uncertainty and change.
In the 1990s, “interim use” emerged as an independent planning and participation instrument. Projects such as “Kalkbreite” in Zurich, “Praterinsel” in Munich and “Holzmarkt” in Berlin show how innovative districts can be created from supposedly worthless areas. The transformation of brownfield sites into urban gardens, cultural centers or communal housing projects has become the guiding principle of a new, open urban development.
Today, in-between spaces are experiencing a renaissance – not as a problem, but as a resource. The debate about the “post-pandemic city” has shown how important flexible, informal and low-threshold open spaces are for the social and ecological balance of urban spaces. Interstitial spaces are an expression of a culture of change, appropriation and resilience – and challenge planners, politicians and society alike.
Transformation potential: from wasteland to urban laboratory
The transformation of unplanned intermediate spaces into productive, liveable and innovative places is one of the greatest challenges and opportunities of contemporary urban development. This is where it becomes clear whether planning can do more than just draw up paragraphs and plot boundaries – whether it is prepared to moderate processes instead of just delivering end products. The potentials of such transformations are diverse and range from ecological upgrading to social inclusion and economic revitalization.
From an ecological perspective, intermediate spaces are often hotspots of biodiversity. Where humans withdraw, pioneer plants, insects and birds settle. Even small wastelands can serve as stepping stones in the urban biotope network, as retreats for rare species or as green corridors between parks and gardens. Examples such as the “Gleiswildnis” in Munich or the “Park am Gleisdreieck” in Berlin show how former railroad facilities can be transformed into species-rich natural areas that are surprisingly valuable for city dwellers.
Interstitial spaces offer social space for appropriation, encounters and participation. They are low-threshold places that do not require an entrance ticket, do not entail an obligation to consume and do not dictate fixed rules. Particularly in high-density neighborhoods, they are the last refuges for informal activities: children use them as an adventure playground, young people as a place of retreat, initiatives as a stage for festivals, flea markets or urban gardening. Such spaces are also often vital for marginalized groups – they offer visibility, protection and the opportunity to get involved in the city.
Economically, in-between spaces are increasingly being discovered as sources of innovation. They offer niches for start-ups, studios, workshops or pop-up restaurants – and at rents that even young companies can afford. At the same time, they act as testing grounds for new mobility concepts, sharing models or sustainable construction methods. Where the traditional recycling chain reaches its limits, space is created for experiments and new business models. The “circular city” often begins precisely where the market fails.
However, the transformation of intermediate spaces requires a sure instinct. Not every brownfield site has to be built on immediately, not every uncontrolled growth has to be tamed. It often makes more sense to recognize, preserve and moderate potential instead of “cleaning up” it too quickly. Participation is not a luxury here, but a prerequisite for sustainable success. Only when residents, users and owners work together on development can places be created that function in the long term and find acceptance.
At the same time, there are dangers lurking: The commercialization of unplanned spaces can lead to informal uses being displaced and social diversity being restricted. Those who view in-between spaces solely as investment properties destroy their special quality. This is why we need guard rails, innovative participation formats and a planning culture that can withstand the unfinished – and sees it as a resource.
Strategies and challenges: Integrating the unplanned into urban development
The integration of in-between spaces into formal urban development is a balancing act. On the one hand, there is enormous potential – for climate adaptation, social integration, creative economy and urban resilience. On the other hand, planners are faced with the task of maintaining the fragile balance between openness and control, between appropriation and order. The integration of the unplanned requires new instruments, processes and, above all, attitudes.
A central instrument is interim use – the temporary, often experimental use of spaces or buildings before a permanent development starts. It makes it possible to test new ideas, involve local stakeholders and make the value of places visible that would otherwise remain dormant. Successful interim use projects such as the “NUN” in Linz, the “Alte Feuerwache” in Cologne or the “Kulturbahnhof” in St. Gallen show how flexible time frames, low entry barriers and cooperative processes can inspire sustainable urban development.
Participation is another key topic. Spaces in between are ideal for experimenting with new participation formats – from open space conferences and citizens’ juries to digital participation platforms. This is where traditional conflicts of interest can be openly negotiated, unusual alliances forged and innovative solutions developed. Anyone who takes participation seriously must be prepared to relinquish control and moderate processes rather than dominate them.
A particular challenge lies in ensuring accessibility and diversity. Spaces in between are vulnerable – they can quickly be privatized, fenced off or overused. Planners and city administrations must therefore develop mechanisms that guarantee openness and equality, while at the same time preventing abuse and displacement. This calls for legal instruments such as leaseholds, urban development contracts or cooperative sponsorships that safeguard the common good without restricting creativity.
Ultimately, the integration of the unplanned is a question of attitude. It requires planners to have the courage to lose control, be open to uncertainties and be prepared to question their own routines. The classic logic of master plans and development plans reaches its limits here. Sustainable urban development needs instruments that can deal with ambiguity, change and contradictions – and understand the spaces in between not as a deficit but as a resource.
This also requires a new understanding of professionalism. Anyone working in urban development today is less a “doer” than a facilitator, less a technocrat than an enabler. The art lies in shaping processes, opening up spaces and productively negotiating conflicts – while always allowing for the surprising and unexpected.
Interstitial spaces as a future laboratory: perspectives for a transformative planning culture
The future of the city is open – and will be decided in the spaces in between. They are the laboratory for a new planning culture that focuses not only on perfection, but also on process, diversity and change. Anyone who wants to design transformative interstitial spaces must be prepared to question routines, forge alliances and try out new forms of cooperation.
An important approach is to consistently open up planning processes. Interstitial spaces should be seen as a resource from the outset and integrated into development strategies. This means involving informal stakeholders at an early stage, establishing cooperative processes and enabling flexible uses. Cities such as Zurich, Basel and Freiburg show that a proactive interstitial space policy not only promotes creativity, but also social cohesion and ecological innovation.
Technological developments such as digital city models, participatory mapping tools or urban sensor technology can help to make potential visible and create a transparent basis for decision-making. But technology alone is not enough. The attitude is crucial: intermediate spaces must be understood as places of learning, experimentation and negotiation – not as gaps that need to be closed as quickly as possible.
The danger of commercialization remains. More and more investors are recognizing the image potential of informal places and are trying to capitalize on their creativity. It is up to urban society to formulate clear rules and ensure that they are oriented towards the common good. This is the only way to ensure that in-between spaces remain places of diversity, openness and innovation – and do not become the backdrop for the next hype.
Ultimately, transformative interstitial spaces are not a question of chance, but of courage. They call for planners who are willing to experiment, for administrations that moderate rather than dictate processes, and for citizens who get involved and take responsibility. The city of the future will emerge where planning and the unplanned meet productively – and where we give the in-between spaces the stage they deserve.
Conclusion: Interstitial spaces – the unplanned heart of the city
Interstitial spaces are much more than gaps in the urban fabric. They are the places where urbanity is constantly reinvented, where social and ecological innovations emerge, where the “unplanned” unfolds its productive power. Anyone who takes urban development seriously must see in-between spaces as a resource – as a laboratory for new ideas, as a stage for diversity and as a catalyst for transformation. It takes courage, openness and professional curiosity to leverage this potential and shape sustainable urban development. The future of the city does not lie in a master plan, but in a creative approach to the unpredictable. Interstitial spaces are at the heart of urban transformation – and their smartest planners have long known this.
