Deep within the ruins of the Restless Weald, you will discover a relic. However, first you need to go through a series of puzzles to get the relic. Thanks to your cunning and intelligence, you will persevere. This is how you complete the non-stop Weald Ruins in Horizon Forbidden West.
You will find these ruins in the northwest Plainsong on the map. You can easily reach the site just outside of Plainsong. There is also a quest giver in Plainsong who will give you a quest to find the ruins. If you need help finding a place, check out the map above for reference.
When you reach the ruins, go into the center of the area. In a discreet covered area you’ll find a note saying the code you need is the year the building was built. Use the climbing area on the other side of the wall to get to the second floor, where the door is locked. There is another note next to the locked door that says the passcode is on the outside of the building.
Run around the building to find the code. One of the numbers has dropped but the code is 1923. Now that you have the code, it’s time to get the key. Go around the building and find the train carriage. Push it along the rail to the position of the switch track. Use the switch to make the car go in a straight line. Push the cart up to the climbing area outside the building. Climb to the second floor and use the rope to go around the platform with the key.
Go back to the locked door and use the key. Then enter the code 1923 to gain entry. Use the zipline on the other side of the door. When you land, you will see some Firegleam on the wall. Use Igniter to detonate it. You will find that the train tracks lead inside the building.
Go back outside and lead the train back to the track. Use the switch to switch the track back to the curve. Push the train into the building. Finally, hop on the train to the second floor, where the ruins are.
https://www.gamepur.com/guides/how-to-complete-the-relic-ruins-in-the-restless-weald-in-horizon-forbidden-west How to complete the Ruins of Relics in the Non-stop Weald in Horizon Forbidden West