On Genghis Kai's giant earth map as the Dutch on marathon speed and noble difficulty, you can walk right into either Paris or Berlin. (both are possible, but the odds of both is around 20% due to a warrior in the 2nd capital by the time you get there) You can also do this with several other civs as well, both Chinese civs can do it to each other, Babylon and Israel (renamed Sumerians) can take out each other. There are several others in addition to these examples.
On earth 18 civs with the same settings as above, starting as Spain. If the warrior is 2 tiles east of your settler, you can take Rome, Paris, Berlin and Athens if you waste no turns. Any other position for the warrior will stop you from getting Athens, and anything west of the settler will stop you getting Berlin.