By now you've likely heard that while the main story of Assassin's Creed Valhalla is grounded in reality, a separate story exists alongside it that is staunchly rooted in Norse mythology. I don't want to spoil what awaits you in Asgard, but here are some tips on getting there as soon as you can.
Get Your Assassin's Creed Valhalla Settlement Level to 3
You'll need to establish the player home of Ravensthorpe before crossing the Bifrost to Asgard. Follow the story beats out of Norway and you should be prompted to begin building up your settlement upon reaching England. You'll need to build your settlement up using raw materials and supplies gathered during raids; I'd advise you to follow the prompts to build the smithy first.
Gunnar will help you sharpen your weapons and armor to buff you up and get your raids done faster. Take care to raid the lowest-level locations first; walking up on a level 90 raid at level 45 is a death sentence. Continue gathering materials and building shops for the town until your settlement reaches level 3. At this point, Valka, the witch from Norway, should arrive in Ravensthorpe. Don't build anything else until you speak to her.
Pro Tip: After the smithy and the Hidden Ones Bureau, build whichever buildings around town consume the least amounts of raw materials and supplies. The Seer's Hut we'll need later requires an exorbitant amount of these building materials, so it's best to conserve what you can.
Complete the Quest "A Wise Friend"
Valka will prompt you to build a Seer's hut for Ravensthorpe. This is a hefty request; it requires 800 supplies and 65 raw materials. That's several raids' worth, so I'd conserve whatever I could up until that point. Once you're able to return to Ravensthorpe and construct the Seer's Hut, you'll be asked gather flowers for her to complete a ritual. This should only take a few seconds—follow the way points to the waterfall and gather them up. Bring the flowers back to Valka and agree to drink the hallucinogenic potion she creates.
Voila! You're in Asgard! This map is, akin to God of War, a world where Norse Mythology is reality. The map is roughly one-fourth the size of the map of England, so there's plenty to do here—about 10 hours of content if you complete everything. Don't worry about not being able to leave Asgard; you can come and go as you please. Asgard isn't meant to be an early-game location, so I'd anticipate 12-15 hours before most players are able to get there.
There you have it! Asgard is my personal favorite part of the game, so make sure to stop on in whenever you've got the supplies. Say hi to Thor for me! For everything Assassin's Creed Valhalla, find our guides and walkthroughs here.