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The City in the Sky

by Fanny Ciufo

Abstract: Rotterdam is an incredible city, an experimental architecture lab where science, technology, urbanism, and sociology meet unexpectedly. This article is a tribute to this spirit, which is manifested exemplary in the Rotterdamse Dakendagen, the festival of the open roofs. Welcome to a completely new way of experiencing cities. 



There are cities full of memories and tales, where buildings are lost in innumerable conversations, where present, past and future coexist like in dreams. Some are silent, looking desperately to catch a dialogue or a glance between their passengers. Others instead arrogantly show themselves as experienced actresses. They are the protagonists of an everyday drama where a mixture of social inequalities and opportunities smells life. 


And then, somewhere in the Netherlands, there is Rotterdam, between a traumatic history of destruction [1] and a vibrant present. A dynamic, noisy air wraps the buildings, which lie next to each other without competition: the Cube Houses, the Markthall, the de Rotterdam, the Hotel New York, and all the housing. A skyline rebuilt on the wounds of the bombs of the Second World War, with freedom and understated design, shaking off the normative urban approach. 


The secular Rotterdam is fresh; her appearance is of a perfect machine - open, democratic, carefree. Perhaps, this is why it was chosen as the citadel of contemporary architects, where they could finally escape from the dogmatic, weighty, almost sacred idea of architecture. In this apparent lack of stimulus, creativity blooms and new ways of recording and understanding the cities are imagined.


Rotterdamse Dakendagen [2] was born from this atmosphere; the annual festival consists of opening the terraces of over 40 roofs for a weekend, some famous, some completely unknown, some public, and some private. It is a slightly ironic invitation to change the point of view, to unpredictably encourage the exchange of smiles between the top of the buildings.


The frenetic up and down creates an artificial landscape of terraces, bridges and hanging gardens, a city in the sky to see the present, remember the past, and imagine the future. Surprisingly, another significant moment in history when Rotterdam was experienced from above was during the Second World War when bombs were dropping in catastrophic circumstances. The historical pictures reveal the emptiness and loneliness of the destruction; there are no buildings, just black and white heaps of rubbles. 

This time, citizens take this bird’s eye view gently and colourfully to celebrate the skyline and the city’s reconstruction.


In this article, I seek to record the spirit of the event as it relates to the history of Rotterdam, while analysing the social and identity implications. Furthermore, we explore the impact of different long term projects on the urban environment, made visible by the festival, and discuss the potential of further developments.


Finally, we conclude with a design proposal: a vision of how to create a permanent nomad twin-city on the roofs, a maze of spaces, and flexible structures that connect the top of the buildings. 


The core proposal concept centers on the possibilities of roofs as a new artificial landscape, a city in the city, and a resilient answer to the imminent rising of the seas due to climate change. 



The Netherlands has a special geo-morphological appearance; its flat landscape strictly interconnects with the sea. The sophisticated dams are the guardians of a population of expert sailors and engineers, protecting a unique land below the sea level. Rotterdam is Europe’s largest port- the name itself derives from the city’s origin as a dam in a small river (the Rotte). In this maritime horizontal city, robust, healthy seagulls yell in the air while the smell of salt blends with the one of fried fish from the market. Cancelling out the vivid memories of the bombardments during the Second World War, life is crawling with activities and events.


Rotterdamse Dakendagen (Rotterdam rooftop days), is an event which happens the first weekend of June, when the rooftops of over 40 buildings are open to experience the urban scene in a completely different way.


Since the beginning in 2015, this event has been a success. During the 2019 edition, over 22,000 urban explorers participated, starting their journeys to discover Rotterdam from a unique point of view.  The city transforms into an open-air museum, it is possible to access the festival in three different ways, buying a ‘Dakpas’ (€8.50), by booking a tour (€12.50) or by experiencing one of the thirty special events such as concerts, theatrical performances, dinners, lectures and symposia. The limited dimension of Rotterdam allows people to navigate easily from building to building, by walking or using the bike.  It is fascinating to see how Rotterdam becomes this hybrid: both a place of passage and routine, but also a dynamic museum under the sky. The city is deconstructed, broken and exploded into  endless exhibits, beyond borders and walls, through stairs and lifts, focusing on the interactions between the visitors, granting them the richness of the urban environment. It is a remarkable, revolutionary, overturning experience.


Interestingly, the phenomenon is not confined to monuments, but it is extended all over the urban fabric, including private buildings and residential ones.The non-hierarchical horizontal approach, embedded in the Dutch culture, is reflected in the catalogue of open terraces. In this network, historical, industrial, public and private spaces come together in dialogue upon the future of the city. It is incredible to observe the variety of installations and design projects that pop up every year, encouraging a playful approach to the urban environment. 


For example, terraces of a parking garage may transform into a plant supermarket and a life-size bamboo maze. Jan Prins School’s rooftop, next to the Markthall, was converted into a gym in the sky. Similarly, on the top of Groot Handelsgebouw, a multi tenant business building symbol of the reconstruction, is a place where visitors enjoy a children’s playground. Finally, the highest buildings, with a spectacular 360-degree view of the city - like the central post, the skybar Maassilo, or Las Palmas - act as special windows to the city. All the rooftops become a stage for events, parties, lectures and art installations.


The heart of the festival is around the Luchtpark Hofbogen, the rooftop of the former Hofplein Station - 16 arches recognized as a national monument in 2015. The central station was bombarded in 1940, with significant damage to the head station, roofing and platforms, and was rebuilt in 1950. In 1990, it was demolished because of the construction of the NS railway tunnel under Blaak. Nowadays, what is remaining of the platform - the long rooftop with the existing canopy - has a vegetable garden, while architectural pavilions appear from time to time. On summer nights, Luchtpark is the perfect venue for parties and events, like open-roof cinema. 


The Luchtsingel [3], a 400-metre-long yellow pedestrian bridge, designed by the Dutch firm ZUS, connects the top of the arches to the Dakakker, the first harvestable rooftop in the Netherlands, a particular piece of landscape lost in the city. The relation between Luchtpark and Dakakker is the most revolutionary and progressive part of the city; the dialogue of terraces, bridge and green spaces is a small manifesto of a new way of designing cities. The continuous alternation of nature and urban environment is one of the strengths of the event. This successful urban intervention is where everything started, and the main inspiration for the movement of the rooftop. It is an alternation of nature, heritage and urban environment.



In 2019, thanks to the initiative taken by Faro (Portugal) and following the Rotterdam example, the European Rooftops’ Cities Network started. Within the last few years, cities from all over Europe joined the group, including Barcelona, Amsterdam, Antwerp, Linz, Prague, Milan and Nicosia. There is even early momentum to bring the project to Seoul, South Korea.


The MOU, Memorandum Of Understanding, is a short document that summarizes the reasons, the objectives, and the finalities of the organization [4]. Some key points are the desire to create a sense of community, enlarge cultural and artistic events in the city and, in particular, acquaint people on the potential of rooftops⁴. They can be a tool to establish energy-efficient projects, to increase local food production, contribute to making our urban environment greener and healthier, and reducing temperatures in cities.


Since the beginning, the Rotterdamse Dakendagen invites reflection upon density in cities, urban configuration, and vision for the future. Many ideas come out from the event, looking for a more stable proposal to use all year [4]. For example, the global Tiny House Movement has expanded to incorporate unused roofs as potential building sites, small, fully-fledged, detached, completely self-sufficient homes of up to 50 m2. Architects promote different activities to encourage people to live firsthand through radical experimentation. For instance, in 2018, visitors could sleep on the former Hofplein Station in six sleeping cabins designed by artists and architects, titled the Rooftop Urban Sleep Spaces (RUSS). Cultural anthropologist Renée Rooijmans and Laurens van der Wal from Walden Studio, designer of the first Dutch Tiny House, started the Dakdorpen project (‘Rooftop Villages’), acknowledging that the sense of community is one of the most important features to take into account.


The idea of participation, community, and the involvement of citizens in the process of redefining and transforming existing roofs, is reminiscent of the approach discussed in the manifesto ’une architecture habiteè’ by Lucien Kroll. Mainly what comes to mind are his sketches of how the linearity of modernist architecture can be broken and deconstructed by the process of participatory design [5]. In this scenario, the roofs from a mere architecture’s shape become the sophisticated space of imagination and desire - really overcoming Le Corbusier’s idea of the green roof [6].


In the 2019 edition, two sites implemented the experiment: the De Kroon building, where they built some wooden frame houses, and the green rooftop of the Thornico Building and Westblaakglass, where they imagined and realized a glasshouse entirely transparent for sleep under the stars.


Other exciting architectural studies have explored the possibility of bridging different rooftops between each other, focusing on the design of the vertical connections, stairs and lifts. Winy Maas, one of the founders of the architecture firm MVRDV, has been active in proposing these types of structures. In 2016, the architect designed a large staircase, where thousands of people could climb from the square in front of Rotterdam Centraal Station to the Groot Handelsgebouw rooftops. Currently, they are working on a proposal for bridges between the buildings, to connect roofs near the train station. The idea of climbing between bridges and platforms brings to life the sketches of Yona Freedman, where megastructures were inhabited by nomads beyond race, nation and religions. This is also reflective of Rotterdam, a multicultural city where different languages and idioms clash together with unpredictable results.


Finally, the human relationship with the sky and stars, the human impulse to reach out to the infinite, calls to experiencing the sublime. Wandering around the roofs is crushing and decenters ourselves, putting us in front of the infinity and immensity of our vision. It is like breaking our comfort zone and opening to the imagination [7]. In this lack of certainty, the chain of people designing, visiting, living, and exploring roofs becomes stronger and more central to defining the vision of the future city.



The main proposal is to rethink Rotterdam from the point of view of the open roof event. It envisions a city with a labyrinthic landscape of stairs, lifts and bridges - adding a new layer to the complexity of the city. 


The design conceives of three main points, enhancing some of the reflections derived from the analysis of the festival. They are directly inspired by the context and aim to expand upon the existing soul of the city.


- Luchtpark and Dakakker - harvesting rooftop

- Luchtsingel - bridges and connection

- Harbour - city in the sky


The transformation is imagined in three different stages. In the first one, there would be a maximization of harvesting on top of the modernist concrete rooftop with plants, trees, vegetables and fruits, so that the citizens can benefit from their food. However, green areas are not only production space; they could also be playful entertainment parks where one can preserve biodiversity and find peace. I imagine a butterfly garden, a forest or a playground, where now it is nothing more than concrete slabs. What if inside our building, on the rooftop, we can find a cafè where we can sit and enjoy the sun, maybe drinking a roof-made juice? What if during a cloudy day, we can enjoy the trickling of rain in a transparent dome on the roof, looking at the city around us? What if these rooftops could also transform into job opportunities, where the main aim is to create a sense of community, help, social care, increasing the quality of life? What if, when we feel trapped inside our flat during the pandemic  [8], we could just sneak onto the communal terraces, sitting in a room without a roof?


In the second stage, rooftops could be connected; this should be achieved with really short and light infrastructure. Like this project, this system of connection should be then clearly organised according to the specific function, maybe connecting two neighbouring residential buildings or individualising mainstream routes around the station. Bridges should be designed carefully, and they should have a minimum impact on the ground below in terms of sunlight and physical barrier. Even more interesting would be the design of stairs, ramps and lifts to make these rooftops accessible to everyone. Some of these could become stages and tribunes for open performances, for music, art and public debate.


Space is then deconstructed in many different directions, making the citizens able to see the city, triggering new ways of experiencing it. Space explodes as in an Escher painting. It is impossible to define up and down; everything moves and changes according to the rhythm of the city. The reflection, especially in the time of the pandemic, is that we are ready to go outside the box of our typical interior rooms and the predictable linearity of our city, to discover new ways of recording cities where the sky is a protagonist.


Finally, there is Rotterdam as a maritime harbour city, in the Netherlands, where the

relationship with the sea is both dramatic and beneficial for the economy, a country where sailors and merchants used to navigate the abysses of the ocean. The work WATERLICHT, of the Dutch artist Roosegaarde, is a virtual flood made by LED lights showing how high the water level could reach - underlining the power and poetry of water. The inextricable and robust relation between Rotterdam and the water could give to the rooftop a new meaning and significance  [9]. It is not absurd to picture a resilient city, not as one trying to stop the sea, but as one adapting and accepting it. Would not then rooftops be the safer place to be?



Rotterdamse Dakendagen is a provocative event that pushes people to think about their city from a different point of view. It is a weekend of reflection on public space, urbanism and the future of the built environment. The richness of the experience derives from the assemblage of different groups of people, private citizens, anthropologists, architects, urbanists and tourists.


The festival, rather than answering questions, is an incredible experience to ask ourselves about the city of tomorrow, prompting projects that will have a significant impact on Rotterdam and its citizens.


The Rooftop project itself is a movement, spreading around many cities in Europe and around the world. It is beneficial to think about urban space innovatively and creatively, encouraging the process of participation in and sharing of misused places. Terraces, hanging gardens, and roofs, are resources - especially in a world that is always more and more stressed by the effects of climate change and global warming. For this reason, the event should not be limited to just a weekend, but should become a continuous and perpetual strategy to lead to substantial changes in the urban fabric. In this sense, Rotterdam, which had the strength to rise from its ashes like a mythical phoenix, is a place of curiosity, energy and unconventional thinking. 


After looking at a desert land, destroyed by the bombs, one must look proudly at the present, and start to imagine the city of the future. I like to imagine a growing, messier Rotterdam - no longer flat, - where floating platforms grow into the sky with gardens, where urbanism is not about regulations but imagination once again.

[1] Werner Warmbrunn, The Dutch Under German Occupation, 1940–1945 (Redwood City : Stanford UP. 1963).


The 14th May 1940, during the Second World War, the entire city centre of Rotterdam was destroyed by bombs by German aviation. Hitler sought to conquer the nation in one day, but it received strong opposition. Tragically, almost all the buildings in the city centre fell except The City Hall. 80,000 civilians became homeless, and 900 civilians were killed. The reconstruction of Rotterdam started in the 1950s, with significant development through the



[2] Daken : roofs, 

      Dagen : day

[3] ‘Crowdfunded Luchtsingel pedestrian bridge opens in Rotterdam’, (accessed 13 March 2021)


Luchtsingel: air canal

The structure has been described by the architects ZUS as the “world’s first crowdfunded public infrastructure project”. 

An extraordinary example of participation and architecture, the initial fundraising came from a crowdfunding campaign, supported by 8000 people. The names of the supporters are inscribed into the wooden boards that clad the bridge for every €25 donated. The main aim was to reconnect two areas of the city separated by the railway.

[4] MOU, rooftops for Europe, memorandum of understanding, available at

(accessed 2019)

[5] Patrick Bouchain, Simon et Lucien Kroll, une architecture habitèe (Arles : Editions Actes Sud, 2013).

[6] Charles-Édouard Jeanneret, Towards a New Architecture (Mineola: Dover Publications, 1985) pp. 61-63.

[7] Mark Dorrian, The Aerial Image: Vertigo, Transparency and Miniaturization (New York: Parallax Press, 2009).

[8] This article has been written during the first lockdown due to the Covid-19 virus. During the problematic months of confinement, terraces and balconies have become the real protagonists in people’s everyday lives.


[9] IPCC The Ocean and Cryosphere in a Changing Climate available at (accessed 2019)


In many ways, sea rise seems impossible to avoid due to the effects of climate change and ice melting caused by decades of carbon emissions. According to IPCC (the Intergovernmental Panel on Climate Change), the sea will rise 30 to 60 centimetres by 2100 in the most optimistic scenario. The UN body has also warned that it is not unlikely that the sea could rise by more than a meter by 2100. The Netherlands, given its low elevation, is one of the countries more at risk in this scenario.


[Image 1] View from the roof of Las Palmas. 


Image by the author (02/06/2019)

Rotterdam Dakendagen
Rotterdam Dakendagen

[Image 2] Map of the main roofs open during the Rotterdamse Dakendagen

[Image 3] Op Het Dak, 

Dakakker harvesting rooftop.


Image by the author (02/06/2019)


[Image 4] Luchtpark Hofbogen


Image by the author  (02/06/2019)

Untitled-5-01 Kopie.jpg

[Image 5] Design proposal along Lijnbaan


Image by the author (2020)

All Images


Charles-Édouard Jeanneret, Towards a New Architecture (Mineola: Dover Publications, 1985).


Ed Melet, Eric Vreedenburgh, Rooftop Architecture: Building on an Elevated Surface (Rotterdam: NAi Publishers 2005).


Mark Dorrian, The Aerial Image: Vertigo, Transparency and Miniaturization (New York: Parallax Press, 2009).


Patrick Bouchain, Simon et Lucien Kroll, une architecture habitèe (Arles : Editions Actes Sud, 2013).


Sabine Lebesque, Helene Fentener van Vlissingen, Yona Friedman: Structures Serving the Unpredictable (Rotterdam: NAi Publishers, 1999).


Simone Schleifer, Marta Serrats, Mireia Casanovas Soley, Cloud9: Rooftop Architecture (Barcelona: Loft Publications, 2010).


Werner Warmbrunn, The Dutch Under German Occupation, 1940–1945 (Redwood City : Stanford UP. 1963).


Online References

‘Contemporary Tiny House / Walden Studio ‘, (accessed 18 May 2020). 


‘Crowdfunded Luchtsingel pedestrian bridge opens in Rotterdam’, (accessed 13 March 2021).


‘dakdorpen’, (accessed 24 April 2020).



(accessed 01 May 2020). 

(accessed 10 May 2020).


IPCC The Ocean and Cryosphere in a Changing Climate available at (accessed 2019).


‘luchtsingel rotterdam’, (accessed 24 April 2020).


MOU, Rooftops for Europe, memorandum of understanding available at (accessed 2019).


‘Pop-up city, Rooftop Futures. Amsterdam: Pop-up City’, (accessed 13 March 2021).


‘rotterdam festival’, 

(accessed 13 May 2020). 


‘rotterdamsedakendagen’, (accessed 01 April 2020). 


‘rotterdamsedakendagen’, (accessed 24 April 2020). 


‘Speeltuinen voor de verbeelding: Een essay over daken. Rotterdam: Rotterdamse Dakendagen’, (accessed 13 March 2021).


‘the stairs to kriterion’, (accessed 03 April 2020). 


‘Tiny House Nederland ‘, (accessed 13 May 2020)


‘waterlicht’, (accessed 01 April 2020). 

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