Harvest Space Elevators

The 7 Harvest Space Elevators were responsible for the transporting cargo and Humans between the Tiara and the capital city of Utgard, maintained by the AI Sif.

History
During the First Battle of Harvest it was used to evacuate the remaining population, after the Covenant began glassing the planet. After the Tiara was destroyed, the Space Elevators collapsed to the surface, the strands that survived the collapse were buried by Mack to protect them from the Covenant's plasma bombardment.

Trivia

 * Harvest having 7 Space Elevators is yet another seven reference.