The UNO city was built in the 1970s to host some UN agencies which had offices in Vienna. The impt agencies are the International Atomic energy and the other is Industrial Development Organisations.
The interesting bit is that the Austraian Govt has leased the buildings to UN for a mere 1 Austrian Schilling (which is less than 1 cent euro) per year.
It was a bit difficult to picture the building with the schorching and blinding sun all over the open area.
There are so many gifts from the UN members and they are displayed all over
...you have outdoor huge bells from Japan, cherry blossom plants even....and in doors there are stones from the moon a gift from NASA, China gift of a (not real) Xian terracotta warrior! and many many more...
Some of the most important organizations like the International Atomic Energy Agency and The United Nations Industrial Development Organization, among other agencies of the UN are based at Vienna.
The United Nations and Secretary General Kofi Annan jointly won the centenary Nobel Peace Prize (2001) for working for human rights and to defuse global conflicts.