Salesforce Tower, 110 Bishopsgate (formerly Heron Tower) is a commercial skyscraper in London. It stands 230 metres (755 feet ) tall including its 28-metre (92 ft) mast which makes it the tallest building in the City of London financial district and the third tallest in Greater London and the United Kingdom, after the Shard in Southwark and One Canada Square at Canary Wharf. 110 Bishopsgate is located on Bishopsgate and is headquartered in Camomile Street, Outwich Street and Houndsditch.
Construction of the building started in 2007 and has been completed in 2011.
The Aon Center (200 East Randolph Street, formerly Amoco Building) is a modern supertall skyscraper just east of the Chicago Loop, Chicago, Illinois, United States, designed by architect Companies Edward Durell Stone and The Perkins and Will partnership, and completed in 1974 as the Standard Oil Building.With 83 floors and a height of 1,136 ft (346 m), it's the fourth-tallest construction in Chicago, surpassed in height by Willis Tower, Trump International Hotel and Tower, and Vista Tower. The building is managed by Jones Lang LaSalle, which is also headquartered in the building. Aon Center formerly housed the world headquarters of Aon and Amoco. Aon still maintains headquarters of its US operations there. The building is also the co-headquarters of Kraft Heinz. Source: Wikipedia