Hot dang, but “The CIty on the Edge of Forever” is a great TOS episode. I mean, this is known, Khaleesi, but having just watched it again I feel compelled to reiterate.
Bonus points for finally sending Uhura on an away mission (at least I think it’s her first), and for being one of the first American TV episodes to say “hell” as profanity. Also — as mentioned in that Kirk article that was making the rounds — Kirk’s romance with Keeler is heartwrenching, evidence that he is not the womanizing stereotype the character has been twisted into.
Also, this is the first reference to Nazis in Trek, and boy did it feel weird in our current climate. I.e., how sad is it that we no longer live in a country, apparently, where you don’t have to explain that Nazis are awful — you can just reference them and assume viewers will be horrified.
Anyway, the Wikipedia article on this episode is a good read, as the story of this episode’s production is a doozy.