Oslo, the name sounds like the main character in a comedy sitcom. A goofy puppy in a cartoon? No? Must be me being weird. Anyway, you need to keep a few things in mind when visiting the capital of Norway. It's a part of Schengen but does not belong to the actual European Union. It's expensive but not for the sake of being expensive. The prices are high but you see where the taxes are going to, it's one of the best places to live in on earth. I'd go as far as calling Norway the European Emirates because of the quality of living. Also because of the largest oil deposits outside of UAE. As an interesting article in the Independent reported (https://www.independent.co.uk/environment/norway-oil-drilling-arctic-ban-labor-party-unions-a8861171.html) they actually refused to drill for oil in their Arctic territories. That is a big deal in these times of global warming. Sacrificing personal gain for the good of the environment? Go Norway! I know that the "hidden gem" term is overused but Oslo is definitely a hidden gem.
When planning a trip, I'd recommend taking a small detour, fly to Gdansk and take the ferry to Oslo. It's an amazing experience and gives you a bit of a taste of Baltic waters. What to do when you arrive? Start with the museums, they're all bunched up in one place around the Bygdøy peninsula. Learn about fascinating Viking long ships they used to traverse the Atlantic Ocean at the Viking Ship Museum (https://www.khm.uio.no/besok-oss/vikingskipshuset/). Visit the Fram Museum (https://frammuseum.no/), or as I like to call it, the frostbite museum and learn about polar expeditions. Or Kon-Tiki Museum (https://www.kon-tiki.no/) telling the story of an absolute mad Norwegian that took a bamboo raft across the Pacific Ocean. I could go on about others like the Museum of Cultural History, or the Maritime one. Best advice I can give: just take a walk around Bygdøy and enter anything that looks interesting.
Oslo is filled to the brim with cool spots to experience. Visit the Akershus Fortress for an awesome view of the Akker Bryge district. You can see the Oslo National Opera House on the eastern side of the hill. There's even a World War 2 Museum there, if you haven't had your fill of museums by now. Head north and you'll come across the Royal Palace, I think it's nothing special but still worth checking out. Go straight for the Vulkan district if you feel like it. It's an industrial area turned into a haven for the alternative community. It's also home to Oslo's first food market hall and some of the most charming riverside cafes I've ever seen. The market is really cool, the freshest meat and produce you can buy in the city. You can even learn to cook it on the spot, they actually host workshops like that. What's weird is that just a few years ago you wouldn't even find any stalls with fish. They have this huge coastline but they didn't eat fish, they exported most of it to Asia. Imagine this: they export fresh fish and import frozen Tilapia. Even the glorious Norwegian salmon went to Japan where it started the salmon sushi obsession. I'm not even joking. They went back to their fish-eating roots only recently. It's one of a few places in the world where you can treat yourself to whale meat. You can have a shot at this peculiar piece of flesh in the form of sushi, or fried like a steak. They say it tastes like beef. Norwegians love their take on hotdogs, sausage injected with cheese and wrapped in bacon. I'm not too keen, to be fair, injectable cheese sounds wrong. Brown cheese, on the other hand, is delicious. It's a part of this nations' heritage, there's nothing special about it, apart from being brown.
I'm conflicted as to which part of Oslo is my favorite; it's either Vulkan or Akker Brygge. I'm leaning towards Aker Brygge. This bayside district is the beating heart of the Norwegian capital. Keep in mind that it's not the warmest part of the world; it gets COLD during non-summer seasons. There is no better way of warming yourself up than jumping into a sauna. They have those tiny floating sauna-boats lined up along the piers. There are even ladders inside so you can drop down to the ice-cold waters. It's even better when it's summer, people can jump in straight from the sidewalk or a diving platform. It's awesome. In most places on earth you'd get at least a minor dose of radiation from all the waste people throw into the water. Aker Brygge is the place to go for Oslo nightlife as well. Try iconic spots such as the Thief Bar and Latter Restaurant & Bar, they also host the best stand-up comedy events in Norway.