Their combined lives more than spanned the 20th century – the civil war was only two years over when Wright was born and Johnson survived nearly two years after George W Bush invaded Iraq. Between them they possibly shaped American architecture more than anyone else. Such is the idea underlying Architecture’s Odd Couple, which concentrates on the period in which they knew each other, from their first contact in 1931 to Wright’s death in 1959.

At the beginning of this period Wright looked spent, a man whose remarkable buildings of the late 19th and early 20th centuries had changed the course of architecture, but who was now skint, under-employed and widely thought to be dead. Johnson, independently wealthy, was an ambitious young… he wasn’t sure what, but definitely ambitious and probably in an architectural way. At the age of 27 he curated the Modern Architecture: International Exhibition at the fledgling Museum of Modern Art, which brought the modern movement in architecture to the attention of the American public. ... Wright thought Johnson a “propagandist” and a “highbrow. A highbrow is a man educated beyond his capacity.” Johnson considered Wright a man of the past, the “greatest architect of the 19th century”. There would be some softening: Wright seemed to respect at least Johnson’s enthusiasm for architecture and his willingness to take a stand and Johnson would come to praise Wright’s “arrangements of secrets of space”.