As upper post says, it is agreed as place. And you can make a simple test to check it whether its being a center or not.

Any place near North Pole you can use compass in two different places. By comparing the directions of compass needle, depending upon the angle of these two directions whether acute angle or wide angle, you can get if it is a pole or not.
In same way, you can prove there is not a pole in southern somewhere. Then the simultaned directions will splaying the outer places.