The City of London’s tallest building, the Leadenhall Building , has officially opened for business. The structure, designed by architects Rogers Stirk Harbour + Partners, is also known as the Cheesegrater because it is angled at ten degrees to comply with planning requirements protecting views of landmarks such as St. Paul’s Cathedral and the Palace of Westminster.

Prince William, Alan Yarrow (lord mayor of the City of London), Sir John Spurling, John Gildersleeve (nonexecutive chairman of British Land), and Prince Harry.

To celebrate the opening, Princes William and Harry were guests of honor at the Leadenhall Building and were presented with a Lego model of the structure. The model was created in tribute to the pioneering techniques employed during construction, in which 80 percent of the building, including its 18,000-metric-ton steel structure, was prefabricated before being assembled on-site. The 610,000-square-foot, 45-floor tower is 90 percent occupied.

“The decision to develop the Leadenhall Building in 2010 was a bold one,” said Chris Grigg, chief executive of real-estate company British Land, said in a statement. “The full impact of the global financial crisis was still unraveling, and the City of London’s position as the world’s leading financial center was under threat. However, we had confidence that the City would rebound, and resolved to deliver an exceptional building that would attract leading companies from all over the world. I am very proud to say we have achieved that.”