World Federation of Great Towers.
It's a mouthful as well as something a little special.
You might not know it, but John Hancock Center is one of only 32 towers WORLDWIDE with membership to this exclusive club.
Not that you can just 'join' of course - you have to be invited based on a set criteria. Apart from taking the shape of a tower (obviously), each structure must represent iconic architectural design, be symbolic of tourism in the city and provide an observation deck for visitors.