Harstad is a town in Harstad Municipality in Troms county, Norway. The town is also the administrative centre of the municipality of Harstad. …Harstad is a town in Harstad Municipality in Troms county, Norway. The town is also the administrative centre of the municipality of Harstad. The 11.15-square-kilometre town has a population of 21,289 which gives the town a population density of 1,879 inhabitants per square kilometre. It is the second-largest town in Troms county, after the city of Tromsø, and it is the largest town in Central Hålogaland.