The Grave of the Guarded is an archon quest available in The Chasm after you meet Dainsleif.
Your objective is to find out what is going on in the place and how the Abyss is involved.
Here’s a walkthrough and guide of The Grave of the Guarded in Genshin Impact.
Explore the path
Follow the path marked on the map.
Defeat the Black Serpent Knights
You will then have to defeat 2 Black Serpent Knights.
Go to the entrance to the ruins
Now, head towards the entrance to the ruins.
Go to the lit room
Follow the path and head to the room that is lit.
Inside, you have to defeat 2 more Black Serpent Knights.
Continue investigating the ruins
Climb up to proceed further.
Defeat 3 Black Serpent Knights this time.
Then, examine the Hilichurls who are at the corner.
Go to the chamber at the center of the ruins’ summit
You will then need to head to the chamber at the center of the ruins’ summit. Follow the path with the broken floor.
Once you reach a dead end, jump and glide to the other building.
Then, climb up to the upper floor.
Continue to make your way up and you’ll reach the center of the ruins’ summit.
The quest ends here.