Orthíad (also known as Ithrö Zhâda) was a hidden base in the Beor Mountains where Urgals loyal to the Broddring Empire were marshaled under Durza prior to the Imperial surprise attack on Farthen Dûr. Ithrö Zhâda meant "Rebel Doom" in the Urgal language.
While the discussion about the approaching army of Urgals in Eragon took place, Ithrö Zhâda was deduced to be the abandoned dwarven city of Orthíad, deserted after the completion of Tronjheim.
In its prime, the city of Orthiad was said to be the greatest of all the dwarf cities.