From Halopedia, the Halo wiki
Description and purpose
The "meteor" is immense, presumably nearly four stories in height, and it is crafted in a such a way that it would blend in with the surrounding terrain if it had not been so large. Spark theorized that it was originally created by the Forerunners as some kind of beacon or power station connected to the subterranean way station found three kilometers beneath the Pori Meteor.
When the Hannibal family settled in the region in 2474, they likely discovered the meteor as city of Pilvros was formed. By 2505, they evidently had recognized its uniqueness as it was in this year that a building would be constructed over both the Pori Meteor and the way station below the surface.
Research conducted on the meteor or the structure below resulted in humanity's first small-scale quantum photonic amplifier for SATCOM relays, catapulting Jack Hannibal into fame and a lucrative new company, Hannibal Weapon Systems. Hannibal would continue research on the meteor, but it was ultimately made the centerpiece of Hannibal HQ's main atrium by 2558.
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