30 St Mary Axe

  • The building won the Royal Institute of British Architects (RIBA) Stirling Prize in 2004.
  • Its distinctive shape is achieved using a diagonal steel structure - a diagrid.
  • Six spiralling light wells allow daylight to flood down onto the floors.

30 St Mary Axe, known fondly as “The Gherkin”,  is one of the most dramatic landmarks in London. Situated in the main financial district, the 40-storey office has won a unique place in the affections of many, as well as a host of awards. It received the Royal Institute of British Architects (RIBA) Stirling Prize in 2004.

Arup helped architect Foster and Partners to achieve the ambitious curved form of the building by designing its distinctive diagonal steel structure - a diagrid. As well as structural advice, the firm provided fire, security, transport planning, wind engineering and geotechnical engineering services.

The building’s unique form is a response to the constraints of its site. Its shape appears less bulky than a rectangular block, creating public space at street level. It also offers minimal resistance to wind, improving the environment for people on the ground and reducing the load on the building.

30 St Mary Axe has six spiralling light wells that allow daylight to flood down onto the floors, as well as being an integral part of the ventilation strategy. This allows the building to operate without full air conditioning at certain times of the year.

The perimeter diagrid is formed from intersecting steel tubes that frame the light wells. It follows the curve of the building to maximise column-free office space, while keeping the structure stable.

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  • St Mary Axe from afar. Credit Grant Smith.

    'The Gherkin' offers minimal resistance to wind, reducing the load on the building