Lost Tomb of S'sarkth
The Lost Tomb of S'sarkth is a location of pure rumor. As chant has it, ages ago, a powerful Prime king by the name of S'sarkth was obsessed with the fear of tomb raiders some day defiling his resting place. Given how many on the Prime are, he knew that no amount of trap or guardian would be enough to truly protect his remains and possessions for all time. Thus, he instead simply had his court mages simply cast his entire sealed tomb into the plane of Vacuum, to float lost in the void for all time. Of course, there has never been any report of a person actually finding anything that even could be the Tomb of S'sarkth, so for now it's quite possibly nothing more than the barmy ramblings of bored planewalkers.
- Inner Planes, pg.125