I can't recall the source, but I remember reading that you can only become a New Yorker when the phrase "I remember when New York used to be…" leaves your lips. Prior to that moment, even if you've spent a decade in the Big Apple, you're still just a tourist. As a city perpetually under construction, nothing in New York is permanent. The second the city erects a new landmark, apartment building, or attraction, you can set your stopwatch for its inevitable destruction. You may not get to witness the demolition or deterioration of classic landmarks in New York in your lifetime, but it will happen all the same.
In the video linked above, you can watch some gorgeous archive footage from New York in the 1960s that showcases the city in all of its classic splendor. While you're searching for congruencies between retro New York and its modern incarnation, just ignore the fact that the mob ran every back then.