General Information
30 St Mary Axe (formerly the Swiss Re Building, and informally known as the Gherkin) is a skyscraper in London’s financial district, the City of London, completed in December 2003 and opened at the end of May 2004. The building has become an iconic symbol of London and is one of the city’s most widely recognised examples of modern architecture.
Additional Information
With 41 floors, the tower is 180 metres tall and stands on the former site of the Baltic Exchange, the headquarters of a global marketplace for ship sales and shipping information. The tower’s topmost panoramic dome, known as the ‘lens’, recalls the iconic glass dome which covered part of the ground floor of the Baltic Exchange. The gherkin name was applied to the current building at least as far back as 1999, referring to that plan’s highly unorthodox layout and appearance.
The primary occupant of the building was Swiss Re, a global reinsurance company, who had the building commissioned as the head office for their UK operation. The tower is sometimes known as ‘Swiss Re Tower’, although this name is not official.
On the building’s top level (the 40th floor), there is a bar for tenants and their guests featuring a 360° view of London. A restaurant operates on the 39th floor, and private dining rooms on the 38th.
The building is visible over long distances: from the north, for instance, it can be seen from the M11 motorway some 32 kilometres away, while to the west it can be seen from the statue of George III in Windsor Great Park.
History: Highlights
On 10 April 1992 the Provisional IRA detonated a bomb close to the Exchange, causing extensive damage to the historic building and neighbouring structures. After the plans to build the Millennium Tower were dropped, 30 St Mary Axe was designed by Norman Foster and Arup engineers, and was erected between 2001 and 2003.
History: Explained
The United Kingdom government’s statutory adviser on the historic environment, English Heritage, and the City of London governing body, the City of London Corporation, were keen that any redevelopment must restore the building’s old façade onto St Mary Axe.
After English Heritage later discovered the damage was far more severe than previously thought, they stopped insisting on full restoration, albeit over the objections of the architectural conservationists who favoured reconstruction.
Baltic Exchange sold the land to Trafalgar House in 1995. Most of the remaining structures on the site were then carefully dismantled, the interior of Exchange Hall and the façade were preserved, hoping for a reconstruction of the building in the future.
In 1996 Trafalgar House submitted plans for the Millennium Tower, a 386-metre building with more than 140,000 square metres office space, apartments, shops, restaurants and gardens. This plan was dropped after objections for being totally out-of-scale with the City of London and anticipated disruption to flight paths for both City and Heathrow airports; the revised plan for a lower tower was accepted.
Architecture: Highlights
Apart from the untypical shape that the Gherkin has, its architects applied some interesting technical solutions to the building and made it a flagship construction harmonising with nature. Since its completion, the building has won a number of prestigious awards in architecture.
Architecture: Explained
The building employs energy-saving methods which allow it to use half the power a similar tower would typically consume. Gaps in each floor create six shafts that serve as a natural ventilation system for the entire building, even though required firebreaks on every sixth floor interrupt the ‘chimney.’ The shafts create a giant double glazing effect; air is sandwiched between two layers of glazing and insulates the office space inside.
Architects promote double glazing in residential houses to avoid the inefficient convection of heat, but the tower exploits this effect. The shafts pull warm air out of the building during the summer and warm the building in the winter using passive solar heating. The shafts also allow sunlight to pass through the building, making the work environment more pleasing, and keeping the lighting costs down.
The primary methods for controlling wind-excited sways are to increase the stiffness, or increase damping with tuned/active mass dampers. Its fully triangulated perimeter structure makes the building sufficiently stiff without any extra reinforcements.
Despite its overall curved glass shape, there is only one piece of curved glass on the building—the lens-shaped cap at the very top.
Whereas most buildings have extensive lift equipment on the roof of the building, this was not possible for the Gherkin, since a bar had been planned for the 40th floor. The architects dealt with this by having the main lift only reach the 34th floor, and then having a push-from-below lift to the 39th floor. There is a marble stairwell and a disabled persons’ lift which leads the visitor up to the bar in the dome.
In October 2004, the building was awarded the 2004 RIBA Stirling Prize. For the first time in the prize’s history, the judges reached a unanimous decision. In December 2005, a survey of the world’s largest firms of architects published in 2006 BD World Architecture 200 voted the tower as the most admired new building in the world.
Film location
The building featured in recent movies such as “Harry Potter and the Half Blood Prince”, “Basic Instinct 2”, “A Good Year” by Ridley Scott and Woody Allen’s “Match Point”. It also hosts a studio of major business programme on Sky News and appears in British TV productions.