Castellus is a system of 4 terrestrial planets and a gas giant. Carborix and Fiax are the local mining worlds whose resources fuel the industries of the turian colony Digeris. Iritum has the attendant starship-relevant facilities and habitats.

The Reapers turned most of the orbital facilities on Castellus to slag, but on Digeris they face a stalemate against the stubborn turian fleet.

Carborix

Carborix is the first planet orbiting the star Castellus.

Main article: Carborix

Nios

Nios is the second planet orbiting the star Castellus.

Main article: Nios

Digeris

Digeris is the third planet orbiting the star Castellus.

Main article: Digeris

• Mission: Apien Crest: Banner of the First Regiment

Fiax

Fiax is the fourth planet orbiting the star Castellus.

Main article: Fiax

Iritum

Iritum is the fifth planet orbiting the star Castellus.

Main article: Iritum