There is a novella by T. L. Sherred by that name which is famous in sci-fi circles. I remember liking the concept greatly - anyone using the machine could view anything in the past, but not affect it in any way. Once could not become any part of the action and visible in the place chosen for viewing. One could merely watch, as a movie. There is no magical occurrence, no babelfish by which the visitor can translate what is being said. But you can see anything in the past. One can also film it and make it into a movie, which is what drives the story, as the protagonists make several very controversial movies with the machine.
The story doesn't read so well now, as its cynicism about war and whether (at least some) national leaders are good and reasonable seems a tired theme. But it wasn't a tired theme in 1947, it was quite unpopular and controversial. Sherred was one of the first to break free from an over-militaristic, universe-conquering approach based on SCIENCE! If it seems trite now, it was because he was one of the originators then. One can notice something similar in CS Lewis's space trilogy. One has to constantly keep in mind that familiar sci-fi elements have come down to us because they were successful when he first wrote them in the 1940's. Lewis also had a considerable cynicism about humanity - though quite different from Sherred's.
The technical plot device of being able to observe but not affect viewed events in the past remains fresh, I think. It's just fun to play with, and I have played with it many times. One can perhaps game the system a bit by witnessing a crime and then returning to the present and telling detectives where to look - things like that. If your fantasy takes you there, that's fine. Where does your fantasy take you? What would you like to see? I eventually decided the Resurrection, even if one could film it, wouldn't work out as well as an evangelist might hope. What would you actually see that could not be interpreted other ways? It might encourage the faithful, but it would hardly be likely to convert the unbeliever. Still, one of you might have some ingenious solution. Sound/No Sound is an interesting option. As you will.
I would certainly try to get some recording done in places north of the Black Sea around 4,500 BC to get some raw data about Proto-Indo-European. I'd likely have to take a PIE specialist along, though, as we may have completely misread the data from here, and I might record hours of speech by four tribes whose languages were unrelated to ours and went extinct. I might like to hover around Djibouti 50 - 70,000 years ago and see who crossed the strait and then record what that first out-of-Africa language was, as it is supposedly the ancestor of every non-African language since. Closer to the present day, I would go back to my 19th C Scots-Irish ancestor Perley Wallace and scan back until I could figure out where he was born and who his parents were. He appears out of nowhere. I might try a fair bit of genealogy, actually, especially of the lines I have no hope of anyone ever tracing, such as the Neats.
I consider myself adequately warned by Thornton Wilder's "Our Town." It would be perilous to go back and look at one's own life, whether best parts or worst.
Open Time-Travel thread from here.