Unasur

UNASUR is the Union of South American Nations, which is creating an intergovernmental union, similar to the European Union.  All of the countries of South America are members, except for French Guiana, which is part of France and the European Union.  Trinidad and Tobago (just off the coast of Venezuela) has been invited to join.

It has administrative centers in multiple cities.

• The Secretariat of UNASUR is in Quito, Ecuador.
• The South American Parliament will be located in Cochabamba, Bolivia.
• The Bank of the South is in Caracas, Venezuela

Other important cities are:

• Brasilia, Brazil where the UNASUR Constitutive Treaty was signed on 23 May 2008.  The Amazon Cooperation Treaty Organization (which promotes sustainable development) is headquartered in Brasilia.
• Mitad del Mundo, Ecuador where UNASUR became a legal entity on 11 March 2011
• Montevideo, Uruguay, the headquarters of Mercosur, which still exists separately from Unasur.  The city is also the headquarters of ALADI, the Latin American Integration Association
• Lima, Peru, the headquarters of CAN, the Andean Community of Nations
• Cuzco, Peru, where the 2004 South American Summit was held
• Isla Margarita, Venezuela, where the First South American Energy Summit has held in 2007
• Guayaquil, Ecuador, where the 2014 UNASUR summit was held, which announced the concept of South American citizenship and a single passport
• Georgetown, Guyana, the headquarters of Caricom, the Caribbean Community, which is mostly made up of Caribbean countries but includes Guyana and Suriname, also part of UNASUR
• Other cities where summits have been held are in: Bariloche, Argentina; Buenos Aires, Argentina; Campana, Argentina; Mar del Plata, Argentina; Santiago, Chile; Asuncion, Paraguay; Paramaribo, Suriname; Fortaleza, Brazil

Despite all this, it seems that UNASUR has a very small budget, has very little power, and doesn't really do anything other than hold meetings.  But it is an interesting concept.