You are indeed correct, @monikozi. From a website, via Google Translate:
Heggholmen was formerly a separate island in the inner Oslofjord, but in recent decades has been connected to Gressholmen and Rambergøya with stone filling.
At the beginning of the 20th century, Christiania Dampoljemølle built a paint and varnish factory on Heggholmen, a facility that included a small narrow-gauge railway with its own turntable. Neither the factory nor the railway is in operation anymore, but the tracks are still there.
Various industrial activities have been carried out on Heggholmen over the years. There has been both a steam-powered linseed oil press and soap production here.
Remains of the industrial plant are still there, as are the worker's quarters and the school hall.
There are also some private cabins on the island.
The oldest lighthouse in the inner Oslofjord is Heggholmen lighthouse on the northern tip towards Skibsløpet.
Both the lighthouse and the other remains of industrial facilities are protected as cultural monuments. https://jernbane.net/bo/subpage.php?s=3&t=13050#:~:text=Verken%2520fabrikk%2520eller%2520jernbane%2520er,samme%2520gj%C3%B8r%2520arbeiderboligen%2520og%2520skolestua.
You are indeed correct, @monikozi. From a website, via Google Translate:
Heggholmen was formerly a separate island in the inner Oslofjord, but in recent decades has been connected to Gressholmen and Rambergøya with stone filling.
At the beginning of the 20th century, Christiania Dampoljemølle built a paint and varnish factory on Heggholmen, a facility that included a small narrow-gauge railway with its own turntable. Neither the factory nor the railway is in operation anymore, but the tracks are still there.
Various industrial activities have been carried out on Heggholmen over the years. There has been both a steam-powered linseed oil press and soap production here.
Remains of the industrial plant are still there, as are the worker's quarters and the school hall.
There are also some private cabins on the island.
The oldest lighthouse in the inner Oslofjord is Heggholmen lighthouse on the northern tip towards Skibsløpet.
Both the lighthouse and the other remains of industrial facilities are protected as cultural monuments.
https://jernbane.net/bo/subpage.php?s=3&t=13050#:~:text=Verken%2520fabrikk%2520eller%2520jernbane%2520er,samme%2520gj%C3%B8r%2520arbeiderboligen%2520og%2520skolestua.
I love stumbling across industrial archeology!
Oh, shucks.
Good guess though, and something I would definitely be taking photos of!
(I did find some gun emplacements on an adjacent island, but much older, and in the form of cannon)