One of the first-ever sound-on-film documentaries is a compilation of interviews with people aged 70-100 talking about the technological and cultural progress they've experienced during their lifetimes. They describe their memories fighting in the Civil War, watching the construction of skyscrapers on Broadway ("buildings five and six stories tall!"), and working as a woman on the Chicago Exhibition in the 1890s. It is one thing to read about history; quite another to hear contemporaneous, first-hand stories about it.
See the entire video here - https://www.youtube.com/watch?v=0FE30a4J38Q