What do you see first when looking at the old photographs on the left? Almost certainly not the intended subjects. One of the pictures is meant to show the Woolworth Building. Another is of the Brooklyn Bridge. The third is supposed to depict Division Street.

Image The Brooklyn Bridge The walkway across the bridge was not divided into lanes for walkers and bikers in 1978. The financial district looks much the same, save for the absence of the twin towers. Credit... David W. Dunlap/The New York Times

But what the eye goes to today, perhaps before anything else, are those twin silhouettes, once such a familiar background in the cityscape that no photographer could avoid them. What we see now is what is no longer there  the towers that are missing in the companion photos on the right.

The photographs on the left were made in the summer of 1978 for “The City Observed: New York,” a guide to Manhattan by Paul Goldberger, who was then the architecture critic of The New York Times. Random House published it the next year. The images beside them were made at the same sites in 2008.