Is obsolescence unavoidable? Can it be seen as a failure of design or a failure to preserve? Abramson, in his book, writes on several neighborhood/city/regional master plans that were proposed, with a common theme being that a complete overhaul of the built fabric is necessary because of obsolescence. If that is the case, why do some seemingly less dynamic buildings work for so long compared to others (one example being a complex such as Pruitt-Igoe) and what factors affect a sense of obsolescence? As a final thought, who decides what is obsolete?