Forbes contributors publish independent expert analyses and insights.
When Stefano Boeri unveiled Milan's Bosco Verticale in 2014 -- two residential towers swathed in nearly 800 trees, 15,000 plants and 5,000 shrubs -- he redefined what a skyscraper could be. Neither futuristic fantasy nor ornamental flourish, the Vertical Forest became a prototype for weaving living ecosystems into dense urban fabrics, tackling air pollution, biodiversity loss and the alienation of city life all at once. Today, Boeri and his studio, Stefano Boeri Architetti, are exporting this green model to more than 20 countries, from Eindhoven to Cairo, while evolving the concept with timber structures and designs adapted to arid climates. For Boeri, whose obsession with trees began as a child, these projects are not utopian gestures but urgent strategies: a vision of cities where humans, plants and animals coexist in a shared future.
Where does your passion for trees come from?
A great inspiration surely came from Italo Calvino's novel The Baron in the Trees. From this book, read when I was a boy, came a fertile obsession that worked inside me for years. Cosimo, the main character, lives a full and adventurous life in the trees, among the branches of holm oaks, cork oaks, oaks, olive trees, beech trees and chestnut trees. Cosimo lives in the trees and from above, through the leaves and branches, he shares a different perception of space, social relations and history. Hence my obsession, which is not an ecological passion, but rather a precise obsession with trees: the idea of looking at the world through the filter of the branches.
Why is the relationship between the city and nature such an important component of your architecture?
The integration with living nature is not only a choice but an urgent matter. We know that cities play a huge role in shaping the future of our planet, being responsible for at least 75 % to 80 % of CO emissions. Trees and forests absorb almost 40 % of the fossil fuel emissions produced in large part by our cities every year. And as much as we can prevent or lessen our impact on the planet, the only technology that is able to absorb the CO already emitted and thus, in a sense, make up for what we have already done, is the tree. There is no artificial technology that can do what nature already does autonomously through photosynthesis. Therefore, cities have the opportunity to contribute to facing the environmental crisis by preserving existing nature and increasing its presence in urban contexts.
What prompted you to build your first Vertical Forest (Bosco Verticale Milano in 2014) instead of other types of green urban landscaping/architecture?
The idea of building a tower completely surrounded by trees originated in early 2007 in Dubai, when as editor-in-chief of Domus, I was following the frantic construction of a city in the desert consisting of dozens of new towers and skyscrapers all covered in glass, ceramic or metal, and all reflecting sunlight and therefore generating heat -- in the air and, above all, on the urban ground, inhabited by pedestrians. Glass and mineral skins in a city that is increasingly artificial and mineral. During those months, I was starting the project of two tall towers in the center of Milan, and suddenly it occurred to me to make two biological towers: two towers covered not in glass, but in leaves -- leaves of plants and shrubs, but especially of trees. Two towers covered in life.
Integrating living nature into architectural design is not the only solution against climate change, but it can be a starting point that, combined with sensible policies and sustainable technological systems, could play a key role in reversing the climate crisis and improving quality of life for humans, plants and animals in contemporary cities.
Tell me about your "Green Obsession" philosophy.
In our "Green Obsession", our approach to architecture and urban planning, urban gardens, and new parks could be created; city roofs could be transformed into lawns or boundary walls into plant façades; courtyards and empty spaces into green oases. The United Nations Sustainable Development Goals campaign rewards initiatives that mobilize, inspire and connect communities to drive positive change. Selected from over 5,000 entries from 190 countries that covered the entire range of the 17 Sustainable Development Goals, our "Green Obsession" was awarded first prize in the category "Inspire". It encourages a new perspective on cities; promotes global collaboration; supports transformative policy actions. It envisions sustainable cities and communities that prioritize good health and well-being while intensifying climate action through its creative approach to urban planning; ecological connectivity; urban forestry.
How have you developed your Vertical Forests over the years, drawing on the knowledge you gained from each one you have built? How many exist currently or are under construction?
The Bosco Verticale in this perspective was a great "school" for us because it gave us the opportunity to experiment with solutions that were then adopted in other projects. Currently, our studio Stefano Boeri Architetti is involved in 77 projects (architecture, Vertical Forests, urban planning, etc.) in more than 20 countries all over the world, with four green buildings already completed in Huanggang, Antwerp, Eindhoven and Treviso and many others under construction, for instance in Utrecht, Paris, Cairo. Trudo Vertical Forest, the first Vertical Forest in social housing built in 2021 in Eindhoven has been a pivotal achievement and a great milestone for us. Combining the environmental issue with the housing shortage crisis in contemporary cities, it includes 125 apartments at a low-rent budget for students and young couples.
The new Vertical Forests that have been built or are under construction represent for us steps forward, in different directions, towards perfecting and adapting the typology: cutting costs with sustainable and innovative technological solutions; creating an accessible and inclusive building; radically changing the urban landscape and the expectations of the population for a future sustainable city in a place where pollution is a very serious problem, as in Huanggang in China; or adapting to a different climate context, even the more arid ones, as in Egypt or Dubai. We are dealing with various scales, different functions and contexts, always trying to move forward in specific aspects while taking into account the objectives and specific project conditions.
What new evolutions of the Vertical Forest are you studying?
In terms of "Vertical Forest prototype" evolution, one of the perspectives we are most curious and glad to explore is the maximization of timber in architectural structures, which we are developing both in Milan and Paris. The ultimate goal is to achieve a completely timber-based structure, creating a circularity between production and installation, in direct dialog with the issue of silviculture and forest management. We are also working towards the exportation of the Vertical Forest typology to arid climates, facing another challenge in order to meet the climatic needs of the part of the world that most suffers from climate change. Our projects for the Dubai Vertical Forest, presented at COP27, or the Cairo Vertical Forest are examples of these efforts.