The Ark (level)

Summary
The Ark is a mysterious Forerunner device from which all the Halos can be activated. In the end of Halo 2,during the Final Sequence Cutscene Delta Halo is armed and then unexpectedly shut down, causing it to send a superluminal signal to all other Halos in the galaxy, putting them on standby mode. 343 Guilty Spark informs Miranda Keyes and Sergeant Johnson that the Halos must now be activated from "The Ark".

Evidence so far places the location of the Ark on Earth, buried under the African soil near New Mombasa. In Halo 2 the Covenant ship carrying the Prophet of Regret jumped into slipspace, for unknown reasons, just a few hundred meters above New Mombasa. This caused the destruction of New Mombasa, and unearthed a huge Forerunner artifact seen in the Halo 3 trailer. The Halo 3 Announcement Trailer depicts a huge structure firing a beam of white energy straight into the sky, through the center of swirling clouds.

The below evidence supports that this artifact is in fact "The Ark":
 * the Halo Graphic Novel, Second Sunrise Over New Mombasa, a transmission is intercepted between the Covenant assualt forces stating that once the humans have been dealt with, they would start uncovering the Ark.
 * In the real world, a concept sketch found in the DVD (seen right) names the artifact as the ark.

While the above evidence points to the structure in the Halo 3 Announcement Trailer being "The Ark", it has not officially been announced as such by Bungie.

Trivia
The name of the Ark may refer to the biblical story of Noah's Ark (Genesis, chapter 7) that was built to save Noah's family and a number of animals from a massive flood, "the ark saves humanity from the flood."

However, it's also possible that "The Ark" is a reference to the Ark of the Covenant. In the old testament, the Ark of the Covenant, which contains the stone tablets of the ten commandments, is the holiest object of the Jewish faith. (This is the same Ark that stripped the skin from the Nazis in the Indiana Jones movie). The Ark of the Covenant is popularly believed resting somewhere in east Africa.