Muspellheim

In the midst of this clash and din the heavens are rent in twain, and the sons of Muspel come riding through the opening. Surtr rides first, and before him and after him flames burning fire.

- Prose Edda

Muspellheim ("home of desolation") is the southern land of fire and home of the fire giants in Norse mythology. It is opposed by Niflheim, the northern land of mists. When the end comes during Ragnarok, the fire giant Surtr will come forth from Muspellheim to set the world ablaze, burning everything to ashes. The Bifrost Bridge will collapse under his weight. The unarmed god Freyr will be the first to die by his sword.

Sources: Encyclopedia Mythica ☼ Wikipedia