The subject of how twentieth-century architecture ages is highly complex and detailed. But the problem is not only decay: it is also a question of the significance and values that the architectural work acquires (or loses) over time. The decision to demolish the buildings designed by important 20th century architects (residential estates, industrial complexes, single buildings, ...) is not only link to the poor conditions and the need to transformation of the city but is more complex. First, we should consider that no owner would give up a prized object with an economic value without a convincing reason. Here we are dealing with a process in which the architectural product progressively undergoes changes and loses its significance. It is ev...