Tower 42 (then known as the NatWest Tower) was the tallest building in the United Kingdom for 10 years, from its completion in 1980 to the topping-out of One Canada Square in November 1990.
- National Westminster Bank initially planned a tower of 137m (450ft), but after it retained Richard Seifert as chief architect in 1964 he submitted a preliminary design at 197m (647ft). The proposal called for demolition of two historic buildings - the City of London Club (1834) and the small National Provincial Bank. After prolonged investigation, in 1964 the Environmental Secretary upheld a preservation order on the banking hall, but permitted demolition of the City of London Club, and the tower's height was reduced to 183m (600ft).
- On completion, Tower 42 was the world's tallest cantilevered building.
- External cleaning of the building is provided in part by an automated mechanical cleaning system.
- The three cantilevered sections hang from the building's central core and are asymmetrical in height.