Omega

Omega is a large space station built out of a mined-out asteroid in the Omega Nebula, in the lawless Terminus Systems. Today, Omega is a major hub of narcotics, weapons, and eezo trafficking without even a pretense of civilian government or military control. Only mercenary groups have been able to instill a limited order; the most ruthless is an asari syndicate run by the notorious Aria T'Loak.

Lower Mining District
The Lower Mining district is featured in Mass Effect: Redemption, where Feron and Liara confront the Blue Suns who have Shepards body.

Mass Effect: Redemption
Liara T'Soni approaches the station on a Batarian Freighter in order to meet an informant with the news of the missing Commander Shepard. She visits Afterlife and the lowe mining-districts.

Mass Effect: Invasion
Omega comes under attack as Reaper creatures known as the Adjutants break loose from Cerberus's research bases beyond the Omega 4 Relay and invade the station. A Cerberus fleet led by General Oleg Petrovsky and Colonel Raymond Ashe arrives and helps eliminate the Adjutants. The Adjutant attack turns out to be only the start of an attempt by Cerberus to conquer the station and secure exclusive access to the Omega 4 Relay and its treasure trove of Reaper technology. Aria unites Omega's warring gangs to fight against the Cerberus occupation force, but General Petrovsky outsmarts her by taking the entire station hostage and threatening to destroy it level-by-level. Aria surrenders and accepts exile. Cerberus proceeds to take control of Omega, furthering the Illusive Man's plans to counter the Reapers.