Xarabydun
Xarbydun was an ancient Empyrean ruin which the Arcanum discovered. It used to be completely undergroud, only accessible via portal by those level 25 and under. In Hidden Vein the Arcanum Consortium was built above ground from Xarabydun, with NPCs there for various interaction in the Nuhmudira's Boon, Isparian Arms, and Bronze Statues quests. In Festivus Ulgrim the Unpleasant wanted to sample the brew in Xarabydun's bar, so, logically, he destroyed the portal and dug a tunnel down to the town. And thus it's level restriction was removed. With various updates to the Harbinger and other quests the Arcanum Consortium has seen more updates. In Evolution a new vendor arrived selling directions and ingredients for making Alchemical Phials
Getting to Xarabydun
A portal to town can be found in Yaraq. An additional portal can be found in the west branch of Umbral Halls. Portal gems to Xarabydun can be purchased in the mage shops of the original 9 starter towns, as well as the Master Mages.