The history of Brussels Expo started with the construction of five exhibition halls for the 1935 Brussels Universal Exposition. The jewel of this group was Hall 5, known as the Grand Palais, and still used today for the Brussels Expo logo. A year later, the operating company Brussels Exhibition Center, a non-profit association, began organizing exhibitions, trade fairs, congresses and other events. Hall 3 was built in the late 1940s, but Halls 7, 8 and 9 and the Patio were not added to the complex until 1957. In 1958, another Universal Exhibition was held in Brussels. Various buildings were added and a new architectural masterpiece was completed, the Atomium. To this day, the Atomium remains an European landmark and a great Brussels tourist attraction. In 1977, Hall 11 was constructed, followed by Hall 12 in 1989. Four years later, the Auditorium opened its doors for the first time.