From Halopedia, the Halo wiki
Universe and lore
The map is set on an unknown planet, in and around a sizable mountainside United Nations Space Command base. At some point, the Mulsanne-class light frigate UNSC Panama and a CAS-class assault carrier did battle in the skies above the base. Despite the UNSC frigate being unable to score critical damage against the carrier, the carrier was likewise unable to fully engage the frigate, for fear of damaging the facility it intended to exploit. As a result, both ships became locked in a tense stalemate.
The following are locations on the map that are so named on the player's heads-up display during gameplay:
Highpower was initially a "test gym" for Big Team Battle, where developers and testers conducted playtests for BTB. It was made into an actual multiplayer map after positive responses to the map.
The CAS-class assault carrier seen in the skybox of the map is a screenshot of the CAS model created by artist Jared Harris for the Halo-themed fan mod, Sins of the Prophets, whose work is also to be officially featured in the 2022 Halo Encyclopedia.