The Arch, situated in the geographical center of Apotheosis City, is not just part of the city's architecture. It is also an integral part of the ship's systems.

An Essential Monument

As well as being an impressive piece of futuristic architecture, the Arch is a large machine directly tied to the ship's systems. As revealed by Casey-McGeever in Heroic games' first Youtube video, it recovers the free-floating and inert forms of Unobtanium present in the ship's atmosphere, known as Dust. Dust is both a crafting component and the main ingame currency, so the Arch is effectively the mint for Apotheosis City.

Only the top third of the Arch is visible; the rest is below the city's ground level. At the base of the Arch, on each side at that level, are doors which lead to mission areas inside the Arch itself. And to quote Casey himself, "Yes, there will be a badge on the top of the Arch."

A Key Target

Both pure Unobtanium, the material used to power the ship's engines, and Dust are extremely valuable, and not only to the humans on board the ship. This makes the Arch the target of raids and invasions by aliens looking to increase their supply of the rare substance.