Pennsylvania Station was a marvel in its time, but it became a relic, a symbol of a bygone era in a time when the world preferred to look forward; a costly "white elephant" that had to come down to save money. The decision in 1962 to replace the old station and its subsequent demolition ultimately proved to be key moments in the birth of the historical preservation movement--a movement that came too late to save Penn Station itself. But during this period one might on any given day of the week, have seen Peter Moore in the station, carefully photographing the building and the process of its destruction, even as above his head--and above the heads of the 200, 000 commuters who transversed the station each day--cranes were beginning to take down what had been one of the grandest public buildings of the 20th century. Moore visited the Station again and again between 1962 and 1966 to document its architectural form as well as the drama of its ''unbuilding.'' The resulting photographs combine compositionally elegant images of architectural form and details with haunting pictures of glass and masonry stripped away from steel girders as the building is progressively demolished.