Publication of the report "Underground spaces are the future of cities: the examples of Paris and Barcelona" by Rosina Vinyes-Ballbé and Jean-Louis Missika

Long relegated to technical networks and parking lots, underground spaces can now become major drivers of climate resilience, urban regeneration, and sustainable mobility. Using Paris and Barcelona as examples, the authors demonstrate that another way of building the city is possible, by transforming existing structures rather than constantly expanding urbanization.

"The cases of Barcelona and Paris demonstrate that underground spaces represent a valuable resource for addressing the challenges of dense European cities – quality of life in public spaces, urban regeneration, and sustainable mobility."

Refreshing cities through depth

As European cities face more frequent heatwaves, extreme weather events, and increasing pressure on public spaces, the underground is emerging as a largely untapped resource. Just a few meters below ground, the temperature remains naturally stable year-round, offering new possibilities for urban cooling. Paris, for example, has 300 kilometers of underground tunnels in the catacombs, while the "Fraîcheur de Paris" network, the largest urban cooling network in Europe, already supplies more than 850 buildings via over 100 kilometers of underground pipes.

Transforming obsolete infrastructure into new urban uses

The report also highlights the considerable potential of currently obsolete underground infrastructure. In Paris, the "Reinventing Paris 2 – The Underbelly of Paris" call for projects explored the repurposing of parking lots, tunnels, and former underground train stations into logistics platforms, public spaces, facilities, and production areas. The former Gobelins train station, comprising 75,000 square meters of underground space, is currently being transformed into an urban logistics hub dedicated to last-mile delivery. In the 18th arrondissement, a former 3,600-square-meter parking garage now houses "La Caverne," an underground urban farm producing over 100 tons of organic mushrooms annually.

Paris and Barcelona, ​​laboratories of a profound urbanism

In Barcelona, ​​researchers identified 108 underground public parking garages representing over one million square meters, currently largely dedicated to automobiles, including nearly 400,000 square meters that could easily be repurposed. According to the authors, these spaces constitute a strategic asset for European cities facing the ecological transition and the gradual decline of car use in urban areas.

The authors conclude that the future of cities no longer lies in conquering height but in exploring depth: the subsoil must become an active extension of the city capable of improving the quality of life, intensifying urban uses and making metropolises more sustainable and resilient.

The authors

Rosina VINYES-BALLBÉ is a professor and researcher in the Department of Urbanism, Territory and Landscape (DUTP) at the Barcelona School of Architecture (ETSAB) and at the Polytechnic University of Catalonia - BCN Tech (UPC) Spain.

Jean-Louis MISSIKA is the editorial director of La Grande Conversation, the magazine of Terra Nova, and a former deputy mayor of Paris in charge of urban planning.

Find the full report freely available on the Terra Nova website

Image illustrating the article via Depositphotos.com.