Adamant Fortress is an Orlesian fortress constructed by dwarves in the Western Approach that stands on the very edge of the Abyssal Rift - a deep chasm that is believed to run as far down as the Deep Roads.
The fortress appears to be small, but is sturdy, with tall walls made of dark jetstone and metal ramparts. In fact it is built into the side of the chasm with vast halls down below. Once, it belonged to the Grey Wardens who beat back the darkspawn that rose from the chasm during the Second Blight, a symbol of their impossible achievement. Then, it housed more than a thousand men and griffons - with weyrs opened onto the chasm.
With passing years, the Western Approach became a wasteland and maintaining the keep became more and more expensive in the eyes of the visiting Warden-Commanders. The sacrifices of the order became a distant memory to the locals, who despite demon attacks on the area's population considered only the Grey Wardens themselves to truly be in danger from the thin Veil and the darkspawn crawling out of the Abyssal Rift. As personnel dwindled and the griffons no longer helped surveil the badlands, the Wardens ultimately pulled back in disgrace to Montsimmard. At the dawning of the Blessed Age, Adamant fortress was abandoned, having become a symbol of the Wardens' decline in the region.
Dragon Age: Asunder
The keep became a home for the tranquil named Pharamond, who conducted his research there due to the Veil being very thin. The keep's inhabitants supported his research and even sealed the keep at the Lord Mayor's suggestion. As a result of his experiments, the fortress was overrun by demons in 9:40 Dragon. All buildings but the keep itself were burned to the ground, and most of the inhabitants were killed and their corpses were possessed.The only survivor who was found was a female human named Dabrissa.
Dragon Age: Inquisition