Being its own region, you can't just travel there on a horse or foot, you'll have to fast travel. How to Fast Travel to Kaer Morhenįortunately, once Kaer Morhen is unlocked, you can go back to it and the surrounding region as much as you like. This will take a while, especially if you're inclined to do side quests, so it may be wise to accept that Kaer Morhen is only really approachable in the mid-to-late game. Kaer Morhen doesn't actually become available for proper exploration until a certain point in the main story, namely until Geralt finishes the branching main plotlines in Velen, Skellige and Novigrad. However, this only constitutes the tutorial, whereas afterwards you'll be sent to White Orchard as part of the main plot. The earliest point you'll get to Kaer Morhen is actually the very start of the game, where Geralt is cheerfully bathing and spending time with Yennefer and Ciri.
