This proposal aims to transform defunct ventilation shafts along the length of the Circle Line into a network of unique gardens. There are three mains stages, starting with constructing a prototype, installation of the first garden at 23/24 Leinster Gardens, and finally, rolling the proposal out to other ventilation shafts across London.

These shafts - a legacy from the steam era of the early Metropolitan and District Railways - remain hidden across London behind high walls and false facades in an attempt to conceal their presence. Though the shafts are no longer needed for venting trains’ steam, the continued presence of the London Underground below provides an untapped opportunity to introduce never-before-seen environments across the capital. From thirty viable shafts, the one at 23/24 Leinster Gardens, Westminster will be the first and the focus of this project. While others are hidden behind anonymous brick walls, this site is distinct for its false facade.

What we'll deliver:

• Create truly unique green spaces across London for the benefit of local residents
• Provide local residents with an area to tend to plants and enjoy intimate green space
• Provide street-level access to the Garden
• Use waste heat from the London Underground to provide moderated growing temperatures for plants
• Build new structure above the ventilation shaft at 23/24 Leinster Gardens to hold the first Hanging Garden
• Collect and use airborne particles from the London Underground to provide plants with the iron and nutrients they need

Why it's a great idea:

Though London boasts many fantastic parks and green areas, real engagement with natural habitats is limited. While parks do provide ample access to a natural environment, they do so in a very controlled - very public - way, meaning that any sense of shared ownership and personal investment in the local habitat is diluted to the point of non-existence. This project aims to give Londoners an opportunity to appreciate the intimacy of tending to seeds and growth over time. With 40-year waiting lists for allotments this space is much needed, but with space at a premium in London new approaches are required.

With the creation of the Hanging Gardens, the urban legacy of London's industrialisation is exploited in ways that encourage its very antidote, providing quiet spaces to tend and bringing local communities together for the benefit of the local residents, shop keepers, and ecology.

Steps to get it done:

• Construct first Hanging Garden at 23/24 Leinster Gardens
• Open first Hanging Garden and gather feedback from local residents
• Prepare proof of concept prototype in ventilation shaft at nearby Craven Hill Gardens
• Use prototype to inform discussion with engineers, TfL, local council, ecology consultants, and local residents.
• Build additional Hanging Gardens at other Circle Line ventilation shafts, creating a unique green belt throughout London
• Draw up design to agreed specifications/budget and apply for planning permission

The Hanging Gardens depend on forming a unique symbiotic relationship between the city and nature. Rain and sun from above are complemented by the micro-climate below: heat from the trains gives mediated year-round soil temperature, earth is enriched by airborne iron particles from brake linings, and unexpected fauna help sustain the unique ecosystem (e.g. the London Underground mosquito - Culex pipiens molestus - has evolved into an entirely distinct species and provides much-needed pollination at the outset). Natural growth combines with the by-products of an industrial legacy to breathe fresh life into London’s biodiversity and offer new ways for communities to engage with nature.

These biodiversity aims are shared by London Underground. In their Biodiverity Action Plan they describe how they aim to “conserve, and where reasonably practical to enhance, the biodiversity value of LU property”. As such, we hope to enter into talks with LU about the biodiversity benefits possible.