BBC News - London 'cheesegrater' building's topping-out ceremony 18 June 2013 Last updated at 19:42 A ceremony has been held to mark the building of the latest addition to London's skyline. The Leadenhall Building in the City of London, nicknamed "the cheesegrater," has reached 224m (734ft) in height. The office building has been under construction since September 2011 and is due to be finished in 2014. The building's tapered profile was designed to protect the sight line of St Paul's Cathedral from the historic Cheshire Cheese pub in Fleet Street. Graham Stirk, senior partner of Rogers Stirk Harbour and Partners which designed the building, said the structure was unique. He said: "It's 12 years since we embarked on this journey. It's slowed down twice. Suddenly, for it to rise out of the ground at the speed it has, it's difficult to describe. London Mayor Boris Johnson attended the topping-out ceremony at the 47th floor earlier. The building is a joint venture between British Land and Canadian company Oxford Properties.