Natural wonders add a bit of flair to the map. In my last game, Catherine had a city neatly placed in the shadow of the Barringer Crater just on the southern tip of the continent. It was a picturesque scene that I felt guilty shattering with my barrage of rockets and modern armor shells. They also add an incentive to exploration and another possibility for city-state quests. And who doesn't want aesthetically pleasing free happiness anyway?