Park Avenue where it becomes the residences of the rich

Upper East 50's is where commercial buildings suddenly give way to classic old Park Avenue buildings, some of which were among first co-op types in the City...these probably date from 1900-1910, and number among them the works of noted architects such as Stanford White.

I don't know if you can see it so clearly in this photo, but building in center has penthouse structure at top which was obviously added later...

Below, my favorite of parade of abstract sculptures which they have in the middle of Park Avenue on the greenery traffic islands in the center of the Avenue..