The Ancient Barrows

From the introduction: The Ancient Barrows have long been a destination for adventurers looking to prove themselves against undead creatures. The tombs never seem to be emptied of their denizens, no matter how many times some brave party has destroyed all of them. It has been many long years since any treasure has lain within their walls, but the dead still haunt the place, and groups of adventurers continue to risk life and limb fighting them.