The name means "The Castle" but don't get excited. This is a 1947 brick villa operating as a guest house, up in the Holmenkollen hills. You're renting a room in someone's old house, with creaky wooden floors and the kind of atmosphere that leans more "Norwegian cabin" than "hotel." The views over the Oslo fjord from the terrace and common areas are spectacular, and the neighborhood is wealthy, quiet, and surrounded by Nordmarka forest. The Holmenkollen Ski Jump is practically next door.
Here's the critical thing: most rooms share bathrooms. One set of facilities per floor, shared among roughly five rooms. If that's a dealbreaker, you need to specifically book the Family Room or Apartment, which have private en-suites. The standard listings don't make this obvious enough, and people get surprised.
No reception desk. No staff on site. Self-check-in with door codes. If something breaks at 11pm, you're emailing someone and hoping for the best. Sound travels through the old wooden walls, hallway footsteps included.
The shared kitchen is the money-saving move here. Oslo restaurant prices are brutal, and being able to cook your own meals means saving money. Buy groceries in the city center before heading up, there's almost nothing to shop from on the hill. The T-bane gets you downtown in about 20-25 minutes, and free parking is available if you're driving, which is rare for Oslo. The walk from Holmenkollen metro station is short but steep, so drag your suitcase carefully in winter.