The Horizon Forbidden West Relic Ruins are lovely little puzzle boxes that you'll solve to discover Ornaments - holographic remnants of the Old Ones that you can trade-in for a lovely light show in Las Vegas. Although there are actually nine Ornaments to collect, one of which is obtained through a side mission you'll get from Stemmur at Hidden Ember. That means there are only actually eight Relic Ruins to explore and discover throughout the Forbidden West. It's worth noting that you'll need a few story-gated special abilities to solve all the Relic Ruins - specifically the ability to open metal flowers and clear Firegleam. You may also need door codes that you can discover by scanning Datapoints in the area. The documents for these can be found in: Settings > Notebook > Datapoints > Relic Ruins. Here's where to take your Ornaments and how to solve all the Horizon Forbidden West Relic Ruins puzzles.