30 St Mary Axe (The Gherkin)

Norman Foster’s skyscraper in the City of London has a rounded form that earned it the nickname the Gherkin. The steel forms a diagonal grid, and the façade has spiralling light wells that ventilate the building naturally. The shape reduces wind at street level and makes the building look smaller than it is.

The building stands on the site of the Baltic Exchange, which was damaged by an IRA bomb in 1992. Swiss Re had Foster + Partners design a headquarters that was completed in 2003. The round plan and the bulging profile were calculated with computer modelling to guide the wind around the building, and the diagonal steel grid, a diagrid, means that few columns are needed inside.

The floor plates are rotated relative to one another, so that light wells spiral up through the building bringing in light and air. This was meant to give lower energy use than a conventional office building. The Gherkin won the Stirling Prize in 2004 and became one of the buildings that transformed London’s skyline, where contemporary skyscrapers have earned nicknames such as the Shard, the Cheesegrater and the Walkie-Talkie.

• Contemporary architecture
• Norman Foster