In Assassin’s Creed Valhalla, when you visit Asgard, you meet a number of characters from Norse mythology including Ivaldi the dwarf. Eivor asks Ivaldi to make an unbreakable chain for him, and for that Ivaldi gives you a riddle to solve, which is finding Cat’s footfall.
To find Cat’s Footfall, you need to go back to the entrance of the palace of Asgard. This will show up on your objective marker, but as you get closer, the marker will disappear. To get the exact location now, you need to use your raven and it will highlight the area in green.
You will see that right in front of the entrance, there is a pillar with a golden cat statue on top of it. You need to climb up the pillar and go near that golden cat statue. It instantly disappears and jumps to the next pillar.
You need to keep following it and every time you get near it, it just disappears. Keep chasing it until it disappears from a dead end. You will see that there is a ledge from where you can perform a Leap of Faith into a haystack.
Jump into the haystack and the Cat’s Footfall will automatically appear in your inventory. Once you have the Cat’s Footfall, you can proceed on to find the Root of the Mountain, which does require a lot of traveling.