Museum of Science and Industry (Chicago) of Progress event. For years, visitors entered the museum through its original main entrance, but that entrance became no longer large enough to handle an increasing volume of visitors. The newer main entrance is a structure detached from the main museum building, through which visitors descend into an underground area and re-ascend into the main building, similar to the Louvre Pyramid. In 1983, due to increased attendance, the museum started construction of its underground parking lot, located in three underground levels below the front lawn. Construction of the underground parking lot was finished in the 1990s. For over 55 years,
Structure of the Royal Air Force in 1989 Structure of the Royal Air Force in 1989 At the end of the Cold War in 1989 the Royal Air Force structure was as follows: The Chief of the Air Staff was a Marshal of the Royal Air Force, who commanded the Royal Air Force. He was a member of the Chiefs of Staff Committee, the Defence Council, and the Air Force Board, which administered the Royal Air Force. The following position were part of the Air Force Board: The strength of the Royal Air Force in 1989 was 93,300 men. RAF Strike Command commanded all operational Royal Air Force