Hanging Gardens of the Circle Line

View of the Hanging Gardens looking east from Lenister Gardens.

Long section showing the concealed nature of the site in the context of neighbouring streets.

Short section looking west, showing the lightweight tensile structural system and plant cultivation. Fallen leaves flutter skywards in the wake of the tube trains passing below.

Diagram showing the flow of warm air to climbing plants, due to the piston effect of trains entering and exiting the tunnels.

Aerial view of another hidden ventilation shaft in Notting Hill, London.

The facade at 23/24 Leinster Gardens, Westminster.

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Hanging Gardens of the Circle Line

Transform defunct ventilation shafts around the Circle Line into a network of unique gardens

The Hanging Gardens of the Circle Line proposes hopes to encourage people to celebrate the poetry of small things: the intimacy of tending to seeds over time.

The ventilation shafts are a legacy from the steam era of the early Metropolitan and District Railways and 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 steam from trains, the presence of the London Underground below provides an untapped opportunity to introduce never-before-seen environments across the capital. 

From thirty viable shafts, Chris Hildrey has focused his proposal around  23/24 Leinster Gardens, Westminster, a site distinct for its false facade.

The Hanging Gardens would be composed of a dense yet lightweight tensile structure hung over each ventilation shaft.

Rain and sun from above would be complemented by the micro-climate below: heat from the trains would provide mediated year-round soil temperature, while earth would be enriched by airborne iron particles from brake linings. 

Unexpected fauna would help sustain this unique ecosystem (the London Underground mosquito, Culex pipiens molestus, has evolved into an entirely distinct species, for example).

Combining natural growth with the byproducts of an industrial legacy would breathe fresh life into London’s biodiversity and offer new ways for communities to engage with nature.


- Bio-diversity
- Transport


Circle Line

Submitted by

Chris Hildrey


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