The city of Tromsø, in the north central part, was the county seat and an Arctic seaport, and seat of the world's northernmost university, renowned for research about the aurora borealis. The University of Tromsø has an astrophysical observatory located in Skibotn (). Tromsø was the only municipality in the former county with a strong population growth; most of the smaller municipalities experience decreasing populations as the young and educated moved to the cities, often in the southern part of Norway. Harstad is a commercial centre for the southern part of the former county, and has been chosen by Statoil as its main office in Northern Norway.