United Nations  

While not an actual Union of the World's nations, the establishment of such an institution is incredibly impressive. The UN was established after World War II with the aim of preventing future world wars, and succeeded the League of Nations, which was characterized as ineffective. Exists to maintain international peace and security, develop friendly relations among nations, achieve international cooperation, and serve as a centre for harmonizing the actions of nations. It is the world's largest international organization. The UN is headquartered on international territory in New York City, and the organization has other offices in Geneva, Nairobi, Vienna, and The Hague, where the International Court of Justice is headquartered.

                              African Union

The African Union (AU) is a continental union consisting of 55 member states located on the continent of Africa. The AU was announced in the Sirte Declaration in Sirte, Libya, on 9 September 1999, calling for the establishment of the African Union. The bloc was founded on 26 May 2001 in Addis Ababa, Ethiopia, and launched on 9 July 2002 in Durban, South Africa.[5] The intention of the AU was to replace the Organisation of African Unity (OAU), established on 25 May 1963 in Addis Ababa by 32 signatory governments; the OAU was disbanded on 9 July 2002. The most important decisions of the AU are made by the Assembly of the African Union, a semi-annual meeting of the heads of state and government of its member states.

                                   Interpol

An international organization that facilitates worldwide police cooperation and crime control. It is the world's largest international police organization. It is headquartered in Lyon, France, with seven regional bureaus worldwide, and a National Central Bureau in all 195 member states. Interpol provides investigative support, expertise and training to law enforcement worldwide, focusing on three major areas of transnational crime: terrorism, cybercrime and organized crime. Its broad mandate covers virtually every kind of crime, including crimes against humanity, child pornography, drug trafficking and production, political corruption, intellectual property infringement, as well as white-collar crime. The agency also facilitates cooperation among national law enforcement institutions through criminal databases and communications networks. Contrary to popular belief, Interpol is itself not a law enforcement agency