Secondly, I wasn't talking specifically about WW2 or anything, just pre-21st century, so the '50s, the '60s, the American West, French Revolution, etc., etc. Before our own time, like in the shows.
I wouldn't mind visiting the ancient world (besides Rome). Shilla Dynasty Korea during the reign of Queen Seondeok (first Queen ruler of Korea) or the First Unification of Korea under Kim Chunchu (Taejeol Muyeol). Enteracting with the Hwarang of Korea would be very interesting. Or, there could be a preserver planet with said culture(s).