Arcadia ONI facility

This ONI Base is a UNSC Office of Naval Intelligence base in the jungles of planet Arcadia. It is located in close proximity of the Arcadia Forerunner Ruin site. It’s unknown if this is a coincidence, or if the ONI built the base to the area on purpose.

Summary
The base is built onto a plateau, likely called "Beasley's Plateau", it's edge overlooking the valley that contains the Forerunner ruins. It consists of five landing platforms, all of which are connected to a large central field. The base has two Reactors powering it. It also has a hangar and several other buildings around it. There are also multiple air control towers around the base.

The base also extends more along the plateau, having several more installations, mostly roads, fields and air control towers as well as large bunker-like structures.

History
During the First Battle of Arcadia in 2531, the base was apparently attacked by the Covenant during the opening stages of the battle, as much of the base was left in ruins. The UNSC used the landing area of the apparently-deserted base as their base of operations, when they attacked a Covenant base inside a dome-shaped energy shield. They used an air pad on the base to call in Rhino tanks from the in orbit, and placed the tanks on the landing pads on the edge of the cliff. After a few unsuccessful attempts, they managed to destroy the Covenant outposts in the area and breach the energy field. After destroying it, they proceeded down to the valley to investigate the area.

The remnants of the base were likely destroyed when the Covenant returned and destroyed Arcadia in 2549.

Trivia
The Halo Wars campaign level Dome of Light is set on the base, as well as the multiplayer map Beasley's Plateau.