That is exactly the subject of this video, which uses an animated map to show you exactly when certain destinations were discovered, with the timeline for many of them actually being quite surprising. For instance, who would have thought that North America was reached before Portugal for instance? There are plenty of other interesting little tidbits like that to be learned along the way too, with some remote places obviously taking longer to find than others.
So just what was the last place found by humans? I won't spoil the answer, but I will say that it will be quite logical once you learn where it is. There is definitely a lot of interesting things to learn here.