In Dark Souls, which area contains the boss fight against the Bed of Chaos?

In Dark Souls, Lost Izalith contains the boss fight against the Bed of Chaos. The ruined city lies deep beneath the Demon Ruins and forms part of the game’s late progression through the lands corrupted by the Flame of Chaos.

Lost Izalith was created when the Witch of Izalith attempted to recreate the First Flame. The experiment produced the Bed of Chaos, from which demons and the chaos flame originated. The area’s lava-filled architecture, demonic creatures, and fiery visual design reflect that history.

Players sometimes identify the boss arena with the Demon Ruins because the two locations connect directly and share a volcanic setting. They are separate areas, however. The Bed of Chaos is also one of the four required Lord Soul encounters before the player can enter the Kiln of the First Flame. Its battle is unusual because progress depends on destroying parts of the arena rather than simply reducing a conventional health bar.