The Dark Heart, a dilapidated structure, lay hidden in the gnarled depths of the Nightmare Lands on Voss. Scarce historical accounts describe this location as an intricate labyrinth of rooms, some locked and others forcibly breached from the inside. Furthermore, it was rumored that an extensive network of subterranean passageways existed beneath the Dark Heart. This area was rumored to be teeming with tainted creatures and forgotten lore; orbital scans suggested it might be the most ancient construction on the entire world.
Nerrethel, a Sith Lord, dedicated a couple of years to the examination of writings and the analysis of the Dark Heart. This pursuit resulted in the development of multiple hypotheses, including one asserting that the architectural style bore resemblance to that of the ancient Sith from Korriban. This included its alignment with Voss's constellations. After a failed attempt to reach the Dark Heart, Lord Nerrethel's body was discovered at the edge of the Nightmare Lands, his final words regarding the expedition were "it sees".
In the time of the Galactic War, the Dark Heart was the setting for the Battle in the Ancient Halls and the Mission to the Dark Heart.