These buildings are part of the UNO city. They were constructed from 1973 to 1979 to host some international organizations that had their offices in other parts of Vienna. Some of the most important organizations are: the International Atomic Energy Agency and The United Nations Industrial Development Organization, among other agencies of the UN.
Next to the UNO city, there’s the Austria Convention Center Vienna built from 1982 to 1987, with several conference halls, designed by the Viennese architect J. Staber.
In front of the UNO city building you’re currently seeing there’s a skyscraper, let’s take a look at it ...