That radar dome is actually Norways first civilian radardome (also housing its first radar). Originally it was at Fornebu (Oslo) airport until 1993 (installed in the 60's). The control tower is the old control tower at Namsos airport, Norways first short runway airport as such the tower itself was fairly small. The garage underneath is for equipment which is in place at small airports around Norway.
It's all right next to Norway's aviation museum (a part of the civilian side of it) and although you can't enter those at any given time, they are open now and then under some occasions.
Bodø had for a time a Norwegian adapted HAWK system (based on MIM-23B), they only lasted 9 years (1986-1995) when they where replaced by NASAMS. Norway didnt have missile based air defence at air stations until the mid 80's.