Its workshops are where Paragon Hirol conceived his famous improvements to golem resilience and power, and where Hirol's favorite student developed a method for storing refined lyrium that is still used centuries after their conception. These breakthroughs brought Kal'Hirol great prosperity; its passageways are said to have glittered with gold and silver, yet its fall is shrouded in mystery. All that is known of this fortress is that its elite appeared at Orzammar's great doors, exhausted and in despair over the loss of their home.
This section contains spoilers for: Dragon Age: Origins - Awakening.
The Warden-Commander successfully ventures into the great thaig in order to eliminate the broodmothers which reside in its lower levels as well as learn more about the darkspawn civil war. There it is uncovered that two hundred casteless dwarves were the last defence of the fortress in order to give enough time for the rest of the population of Kal'Hirol to escape in Orzammar's safety.
In the epilogue, it is mentioned that Kal'Hirol is cleared of darkspawn, and eventually the dwarves of Orzammar attempt to reclaim it. House Helmi ultimately leads a host of dwarves to clear the Deep Roads between Orzammar and Kal'Hirol, and though the losses were great, they are ultimately successful in 9:31 Dragon.