I really like films that captured something of the time I was born. Friedkin's 1971 'The French Connection' is such a film, and it also happens to be excellent cinema.
Although I have seen the film a dozen times, and I knew that most of the bad guys and the cops were played by actual off duty real life cops, I had not realized that Doyle and Russo's boss was played by Eddie Egan...who was the man that Gene Hackman was portraying. I also had not realized that the cop who followed Sal Boca to DC was Sonny Grasso....the man Roy Scheider was portraying.