Map of Oscarsborg citadel

Map of Oscarsborg citadel

A. island of South Kaholmen, B. island of North Kaholmen

1. Main fort
2. Western shore battery
3. East shore battery
4. Main battery
5. South battery
6. East battery
7. Coastal fort
8. Parade in front of the old barracks
9. Range finder post and Signal battery
10. Torpedo battery
11. Residence of the commandant of the fortress

Oscarsborg's fortified area

 Batteries and other installations in Drøbaksund area

A. Drøbaksund strait, B. Drøbak town, C. Heer settlement

1. Main fort at South Kaholmen island
2. Torpedo battery on North Kaholmen island
3. Battery Husvik
4. Battery Kopås
5. Battery Veisving
6. Seiersten redoubt
7. Infantry strong point Heer
8. Battries Heer
9. Batteries of Håøya island
10. Mine station on Bergholmen island
11. Battery Nesset
12. Battery Luftvern

Gun's mounting plate