You might think that 111 West 57th Street is an extremely thin building. But 111 West 57th Street is undeniably slender in high-rise terms – a super-slender building certainly, and perhaps even a ‘mega-slender’ one. In the global race to build tall, it’s no longer all about height. The other number that everyone wants to know is the aspect ratio: the relationship between a building’s height and its width. 111 West 57th is one of a new breed of towers that are pushing that ratio to previously impossible levels.