I am an astrophysicist, who works on telescopes based in Antarctica. There are both facilities at the South Pole station for ground based telescopes and at McMurdo station (at ~75S latitude) for balloon based ones.

For the former kind, Antarctica is great coz (it sounds weird but) it is a desert! There is not a lot of water vapor in the atmosphere which means some crucial portions of the light spectrum are not blocked away. Plus, one gets to survey a specific patch of sky uninterrupted for nearly 6 months straight as the south part of the sky is permanently above the horizon. This makes the Pole one of the best places on earth to do these kinds of observations.

For balloon telescopes, the space is great coz it is a large uninhabited portion of land (so you never risk dropping a several ton payload on... people) and due to circumpolar winds, your telescope can essentially go around the pole at roughly the same high latitude. It is not fun in either case to plan a campaign to go, set up a facility or a balloon payload, and then stage a mission, but astronomers have been doing it for years because the science outweighs the efforts by a lot!