The Halo is a ringworld that may be crucial to tipping the scales in the war between the humans and Covenant.

It is believed to be an ancient artifact of a long departed race (perhaps the Jjarro of the Marathon series).

According to Bungie, the ringworld has a diameter of roughly 10,000 miles. Doing a little math, we find that the circumference of this artifact is approximately 31,400 miles (considerably larger than the Earth's circumference), and judgeing by images of it in the MWNY Demo, it is probably between 250 and 750 miles wide, giving it a formidable 7,850,000 to 2,3550,000 square miles of surface area, not counting the outside and sides of the ring.

The entire surface of the Halo will not be traversable during the course of the game.

Bungie is believed to have drawn inspiration and/or ideas from in designing the Halo from the novel Ringworld by Larry Niven. Halo.bungie.org administrator Louis Wu took his nickname from the protagonist of that novel.