Architectural history is like other histories in that it is concerned with understanding and finding explanations for the past. Where it differs is in the nature of the evidence available and in the techniques developed to evaluate that evidence. In its initial stages any historical study involves collecting facts. In order to make any sense of those facts they must be selected, ordered, evaluated, interpreted and placed in context. E. H. Carr in What is History? (Harmondsworth, Penguin, 1964) explains this very clearly. History begins today, but one of the main difficulties about studying the recent past is the sheer volume of information available and the problem of determining what is significant and what is not.