How do we know precisely the locations of the geographic poles? And how did we know our location relative to them before GPS?

Question

Basically, how can we measure the Earth’s rotational axis accurately enough to be able to erect a physical [pole](https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Fantarctic-logistics.com%2Fwp-content%2Fuploads%2F2016%2F08%2Fdestination-south-pole-1.jpg&f=1&nofb=1) that goes through it? And how did expeditions in the early 20th century know when they successfully reached the poles?

In: Other

Answer 1

You can measure your latitude quite accurately by observing the position of the sun at noon. Using a sextant and an almanac, you can get to within about a tenth of a mile.

As for physical poles, they are just a decoration, you get it close enough and call it good.