City within a city: How UN headquarters in NY was built (3D VIDEO)

The world will be watching as its leaders take to the iconic green marble hall at UN headquarters in New York to address the world as the 70th global debate kicks off on Monday. But what is this place? And how did it come to be?

Constructed on Manhattan’s Turtle Bay, the UN headquarters may be one of the reasons the less than savory area was transformed into a truly iconic part of the Big Apple. 

It took five years to build the famous 39-storey Secretariat Building, which was completed in 1952. The complex also includes the domed General Assembly Building with its General Assembly Hall that can seat 1,800 people, the Conference Building that holds the Security Council Chamber, the Dag Hammarskjöld Library, and some other buildings.

Another distinguishing feature is the line of flagpoles displaying the flags of all 193 UN member states arranged in English alphabetical order. The line will grow one flag longer this year, as the Palestinian colors will be raised following a resounding vote in September.