Some of the documents in the archives are from or about events everyone's heard of but perhaps haven't seen. Most are about things people don't know about, or at least haven't given much thought to. And sometimes, the documents in the archives are about things that never happened.
Here's an example from the rich and varied website of NARA, the National Archives and Records Administration, the archives of the American federal government: a draft of a statement to be read by President Nixon in the tragic event of an accident which would prevent the return to Earth of Neil Armstrong and Edwin Aldrin, the first two astronauts to land on the moon, 43 years ago this month. (The link comes from this page.) The statement was written by William Safire - and interestingly, the scenario it envisions is that the two men are still alive, just not able to get back.