When archaeologists are puzzled by how the Egyptians could build the Great Pyramids and then a hundred years or so later built crummy pyramids that started falling apart before they were finished, they need look no further than New York.
In the 20's and 30's you saw magnificent buildings like Rockefeller Center and the Chrysler Building and then after the war you saw a bunch of retarded-looking glass boxes that seem to be inspired by crossword puzzles. Things can degenerate astonishingly quickly, particularly in our super-heated modern culture. Look at the churches built in the 19th Century and Soviet-looking brick boxes they put up in the 20th.