122 Leadenhall Street (The Cheesegrater)

122 Leadenhall Street, usually called the Leadenhall Building or the Cheesegrater, is a 225-metre skyscraper with 48 floors in the City of London. It opened in July 2014 and was designed by the architects Rogers Stirk Harbour + Partners, led by Richard Rogers. Its nickname comes from its wedge shape, which looks like a kitchen cheese grater.

The tower stands next to the Lloyd's Building, which Richard Rogers also designed. The name was first used by Peter Rees, the City of London's chief planning officer. When he saw the model, he joked that he could imagine the architect's wife using it to grate parmesan, and the name stuck. The sloping face also keeps a protected view of St Paul's Cathedral clear.

Why a wedge?

London protects certain views of St Paul's Cathedral, so the tower slopes back at an angle to leave those views open. The sloping side is covered with a tapered glass wall that shows steel bracing, and a ladder-like frame makes the building look even taller. The price of this shape is that it has fairly little floor space for its height.

A skeleton on the outside

Most tall buildings are held up by a concrete core. Here a steel frame called the Megaframe, engineered by the firm Arup, holds up the whole structure, and it is the tallest of its kind in the world. The flat side hides the lifts, and like the neighbouring Lloyd's Building, it shows off the machinery, with bright orange counterweights and motors.

At the bottom, a 30-metre-high open atrium extends the public plaza next door.

The site before

The shipping company P&O bought the site in 1845 and had offices here from 1848. In 1969 a 14-floor building, 54 metres tall, replaced the old offices. An IRA bomb damaged it in the early 1990s. It was taken down in 2007-08, building stopped after the 2008 financial crisis, and the project restarted in 2010 under Oxford Properties and British Land.

On the globe

The model shows the white-framed glass wedge tower. Look for the sloping south face.