building

Vienna is the seat of a number of United Nations offices and various international institutions and companies, including the United Nations Industrial Development Organization (UNIDO), the Organization of Petroleum Exporting Countries (OPEC), the International Atomic Energy Agency (IAEA), the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) and the Organization for Security and Co-operation in Europe (OSCE). Furthermore, the 1980 Diplomatic Conference was held in Vienna that led to the adoption of the United Nations Convention of Contracts for the International Sale of Goods. Additionally, Vienna is the seat of the United Nations Commission on International Trade Law's secretariat (UNCITRAL).