Oscarsborg Fortress is a coastal fortress in the Oslofjord, close to the town of Drøbak in Akershus County, Norway. The best known part is situated on two small islets: Nordre Kaholmen and Søndre Kaho
Oscarsborg Fortress' Main Island seen from the south-west.
Oberst Birger Eriksen, the commander of Oscarsborg on 9 April 1940.
Harbour Fortress on South Kaholmen. The 28 cm guns are on this island on the left, the torpedo battery to the right. Scars in the rock are over the torpedo exit tunnels. The Old Barracks in the background
One of the three 28 cm (11.0 in) main battery guns at Oscarsborg.
Drøbak is a town and the centre of the municipality of Frogn, in Akershus county, Norway. The city is located along the Oslofjord, and has 13,409 inhabitants.
Drøbak seen from the Oslofjord