|Airplane on the top of a builiding in Manhattan.|
The biplane on the roof sculpture was designed by some guy named Rudolph de Harak and executed by the sculptor William Tarr in 1969 (thanks Jack Ryan).
Apparently it's a full-size model of a WW1 Sopwith Camel, complete with runway. It was put there to amuse inhabitants of surrounding scyscrapers, notably the WTC.
...the biplane on the roof of 77 Water Street in Lower Manhattan, a playful touch installed by the developer, the William Kaufman Organization.