In which country was OPEC (Organization of the Petroleum Exporting Countries) founded?

Organization of the Petroleum Exporting Countries (OPEC) is an intergovernmental organization of 14 nations as of May 2017, founded in 1960 in Baghdad (the capital of Iraq) by the first five members (Iran, Iraq, Kuwait, Saudi Arabia, Venezuela), and headquartered since 1965 in Vienna. As of 2016, the 14 countries accounted for an estimated 44 percent of global oil production and 73 percent of the world's "proven" oil reserves, giving OPEC a major influence on global oil prices that were previously determined by American-dominated multinational oil companies.

OPEC's stated mission is "to coordinate and unify the petroleum policies of its member countries and ensure the stabilization of oil markets, in order to secure an efficient, economic and regular supply of petroleum to consumers, a steady income to producers, and a fair return on capital for those investing in the petroleum industry." The organization is also a significant provider of information about the international oil market. As of May 2017, OPEC's members are Algeria, Angola, Ecuador, Equatorial Guinea, Gabon, Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia (the de facto leader), United Arab Emirates, and Venezuela, while Indonesia is a former member. Two-thirds of OPEC's oil production and reserves are in its six Middle Eastern countries that surround the oil-rich Persian Gulf.