Which 1967 documentary film, directed by Frederick Wiseman, is a seminal example of the observational documentary, portraying life in an institution for the criminally insane?

'Titicut Follies' is a 1967 American documentary film, directed by Frederick Wiseman. It is a seminal example of observational documentary, which portrays life in a state institution for the criminally insane, without voice-over or direct interviews, letting reality speak for itself.