The French Academy of Sciences performed measurements in Aavasaksa in the 18th century.
Is the Earth shaped like a lemon or like a tangerine? This problem was the subject of heated debate in the scientific circles of early 18th-century Europe. The answer was important for, among other things, navigation and thus King Louis XV of naval might France assembled an expedition party consisting of members of the Royal Academy of Sciences, the leading scientists of their day, and sent them to the far north to resolve the issue.
The expedition was led by Pierre Louis Moreau de Maupertuis. Uppsala University Professor of Astronomy Anders Celsius complemented the expedition with master linguist and future astronomer Anders Hellant serving as its local guide. It is said that Anders Celsius performed the first temperature measurements for his Celsius scale while participating in this effort.
You can find the monument next to the observation tower.