Between 1945 and 1980, roughly as much was built globally as had been constructed throughout all prior history.  Compounding this unprecedented magnitude of construction, the rise of modern architecture through the course of the 20th century fostered many ways of building that fundamentally changed both the nature and the cyclic frequency of material and system renewal that we have come to anticipate in working with ‘traditional’ means of construction.  At the same time, new formal and material paradigms led in many cases – particularly in the 1960s and 1970s – to the construction of large housing, commercial and civic works that – in addition to posing new technical conservation challenges – were often underappreciated by a large portion of the using public.