Lower City is another one of the factions that was added in The Burning Crusade. The Lower City factions main hub is located in the lower portion of Shattrath, I know right. Lower City has quests spread all around Outlands that will raise your reputation with them. However the easiest way to raise your reputation with Lower City is by running the Auchindoun instances. Auchindoun is located in southern Terokkar Forest, It's the large ring.
The instances you can run for Lower City reputation are Shadow Labs, Auchenai Crypts and Sethekk Halls. The fourth instance here, Mana Tombs will award you Consordium reputation. Doing Heroics will give you the best reputation with Lower City. Also, while running Shadow Labs you can collect Fel Armaments and Marks of Kil'jaden to increase your Aldor reputation. If you'd like to watch videos of me soloing Lower City rep, see below.
Instances that Give Lower City Rep: