When it was first completed in 1973, the Aon Center was the tallest building in Chicago and the fourth tallest in the world. Though its stardom was soon dashed by the completion of the nearby Sears Tower (now Willis Tower) later that year, the Edward Durell Stone-designed building continues to maintain a significant presence in the city’s skyline.
In light of its proximity to Millennium Park and other tourist attractions in Downtown Chicago, city officials considered adding an exterior elevator and observation deck to the 1,136-foot-tall Aon Center in May 2018 that swiftly gained approval, as AN has previously reported. Two years later, Aon Center general manager Matthew Amato has confirmed to the Chicago Tribune that a $185 million budget is being secured towards the construction of the tower’s additions by the end of this year, and that the project is expected to be completed by Spring 2022. 601W Companies, a developer and owner of Aon Center, will team with Legends, the New York-based firm responsible for One World Trade Observatory in Manhattan, to develop and later co-own the project. The two settled on a set of designs from Solomon Cordwell Buenz that will only minimally interfere with the sleek, minimal details of the late-modernist tower.
Visitors will be able to access the observatory deck by first entering a new 9,000-square-foot pavilion to be built on the ground floor, followed by a south-facing glass elevator that will provide largely unobstructed views of the city. The observation deck will replace the mechanical services space on its 82nd floor and will include two floors of amenities, including an event space, restaurant, bar, and the Sky Summit, a thrill ride that will take visitors over the building’s edge in a glass-enclosed tube for up to 40 seconds. 601W Companies estimates that the deck’s various amenities could generate up to $40 million in annual revenue—far more than could be received from treating the top two floors as rentable office space.
The observation deck, yet to be named, will become the third in the city (including 360 Chicago at the Hancock Center and the Skydeck at Willis Tower). The additions reflect the second major alteration to the building since 1973; the first was in 1992 to replace the Italian Carrara marble facade with Mount Airy white granite at an estimated cost of $80 million.