Norwegian mapping authority releases approx. 8000 historical maps for download
                    Link (Norwegian)
Just click on the county (fylke) and "Vis historiske kart" and you're set. Click "vis flere kart" to show more.
Alternatively with Google translate.
edit: typo
                            Just click on the county (fylke) and "Vis historiske kart" and you're set. Click "vis flere kart" to show more.
Alternatively with Google translate.
edit: typo
                            
                            
Comments
skal,
Sven
Note that if anyone wish to use these maps for anything, all maps older than 100 years old are considered copyright-free, while newer maps are licensed under the Creative Commons Attribution 4.0 International Public License.