There are many things we don't know but many over the years have been released. many regarding the US military like weapons and also plans. there have been many weird thing like John Lennon's song " I am the walrus", Winton Churchill's UFO sighting, Julia Child's knowledge on WWII, CIA mind control experiment, Area 51, UFO's in the U.S.S.R. plans to kill Fidel Castro, Grand Central terminal secret rooms.