How to get to Kaer Morhen in The Witcher 3

 What you need to do to get to the fortress of Kaer Morhen according to the plot of the game; how to return to Kaer Morhen at any time

Trying to get into Kaer Morhen in The Witcher 3 action role-playing game is a waste of time, as it won't take more than a few minutes before you realize you're running in circles. In fact, Kaer Morhen is blocked by The Witcher 3 storyline, and you won't be able to get into the witcher's fortress until you get the appropriate task as part of the main quest. That is why you should not waste your time trying to get into the fortress from the very beginning of the game.

To get to Kaer Morhen in The Witcher 3, you need to complete the story quest "The Freak". Completing this quest will take you to Kaer Morhen and open up the region for fast travel.

In an attempt to avoid spoilers, I won't go into the details of the Freak's story or the quests that preceded it. However, I will inform you that this task is from the middle endgame. This mission will begin in the second act, its events unfold after some plot (though not the last) twists and turns.

In short, you must complete the story quests in the White Garden, Novigrad, and Skellige, and only then will the Freak mission become available. Once that happens, there are a few tasks to complete before you get to Kaer Morhen and can explore the new region.

At any point in the game, after completing the mission "Freak", you can travel to Kaer Morhen by using the fast travel marker. Moreover, most of the second act tells about the events that happened on the territory of this fortress. Fast Travel to Kaer Morhen will be available at the end of Act 2.