Some reports suggest the move is motivated by relevant tax advantages. Still, Aon’s statements on the subject have focussed on the physical proximity of its London offices to the Lloyd’s insurance exchange and improved access to important emerging markets.
Aon has thousands of employees worldwide and a significant office presence in London, which it plans to expand with a recently agreed pre-let deal to rent several floors at the still-to-be-completed Leadenhall Building in the City of London.
The company was keen to stress its commitment to offices in Chicago, with the Windy City remaining its American headquarters and no jobs being lost as a result of the corporate relocation. As if to make the point, Aon recently agreed to a leasehold deal on a significant area of new offices in Chicago.
“Chicago is the foundation of one of our most important markets, and as the headquarters of the Americas, it will continue to be central to the success of the firm,” said Aon chief executive Greg Case.
“The decisions we make today will help drive our global strategy and strengthen our growth opportunities in the years to come. The continued investment in our international operations and emerging markets is important to the growth of our firm.”
Aon’s recently confirmed commitment to offices at the Leadenhall Building relates to a total of 191,000 sqft of space at the development being delivered jointly by British Land and Oxford Properties.
“The Aon Centre at the Leadenhall Building places us at the heart of the City’s insurance sector,” said Robert Brown, head of Aon’s retail brokerage operations, on agreeing the deal in November.
Editor’s notes: The Leadenhall Building, also known as The Cheesegrater, is located at 122 Leadenhall in the City of London and was completed in 2014.
As of June 2024, AON rented office space on floors 4 to 13 and also occupied space on the ground floor that is used as its reception area.
The firm refers to the space as The AON Centre.
AON maintains its presence in its Chicago office and lists the address as 200 E. Randolph Street, Chicago, Illinois 60601
As of October 2026, Aon remained in occupation at the Leadenhall Building at 122 Leadenhall, which was listed as its Aon Global Operational Headquarters.
The firm also remained in occupation at 200 E. Randolph Street, which, as of October 2026, was the 4th tallest building in Chicago.