Arkology was a massive orbital habitat that served as the site of the climactic season four finale battle against the Magog World Ship. The self-sustained colony came to house one of the Paradine, a being capable of stopping the Abyss so the Magog, the self-proclaimed harbingers of the Spirit of the Abyss, set out to destroy it. Dylan Hunt learned he was one of the Paradines on Arkology.
Arkology was a massive orbital habitat roughly 36 km (22 miles) long, 8 km (5 miles) wide, with a 500,000 km (310,685 miles) orbit anchored into an asteroid. The colony itself pocesses a gravity generation system and slipstream propulsion. Apparently the slipstream was used long ago to move the station into place and hasn't been used since. The station possessed no weapons or defenses leaving it at the mercy of the Abyss when the Magog attacked.
Arkology was home to peace loving people including Nietzscheans, Humans, and other species. The residents of the station believed in a philosophy which embraced total pacifism. This noble sentiment would sadly lead them to their doom after the Magog learned of Arkology through capturing and infesting one of its senior diplomats who was sent to sign a "treaty" with the Magog. The people of the asteroid habitat lived abnormally long lives likely through the use of a technique known as "dream state". Through this unique pyschic link the children of Arkology were taught academic and moral lessons. The "dream state" also allowed the adults a forum to debate and democratically mediate conflicts.