Staying with family friends in Chicago back in the 70s, I had an early introduction to a couple of the world’s great architects. My host was an architect and a lecturer at Northwestern University and the Windy City was for him a giant playground of structural delight. Being a callow youth, he decided my education was incomplete without a tour of the great buildings, accompanied by an historical overview of the skyscraper. So it was that on a busy morning in only a few blocks of the city he unravelled the mystery of these iconic structures, ones we now pass with barely a glance; the early brownstone buildings with an almost classical elegance of form and scale; the shift in materials that allowed things to go higher, be lighter and brighter; the removal of the innards so that internal space and light was created with soaring atriums; hanging structures off internal frames, so that it appeared that buildings were almost floating; the simplicity and splendour of well-balanced design and function in the giants alongside the lakeshore.