The Fortress of Sanctuary is Samantha Arias/Reign's Kryptonian stronghold located in the Desert It also serves as a repository for all the knowledge of the Kryptonians, including that of their now-destroyed homeworld of Krypton.
She then took the Crystal of Sanctuary beacon she found from the ship and followed its light out and into the middle of the desert. She followed the beacon's signal to the middle of a clearing. All of a sudden, the ground shook and pikes made of rock emerged to form creating the Fortress of Sanctuary .
Samantha went inside the structure and placed the beacon into a Kryptonian computer console panel that caused everything around her to activate. A holographic projection emerged, of a Worldkiller Hologram, and told her she had answers for her questions. Sam asked what the place they were in was, and the projection responded by saying that they were in her Fortress of Sanctuary. Worldkiller Hologram tells her that the Fortress is a a piece of her world, the dead planet Krypton. so Samantha Arias/Reign fulfilled her destiny. Then Sam's mind was altered by the experiments that were made on her and she became a world killer.
Interior Design: Reign's version is a blackened cave, with crystal-like rocks protruding from the ground and a dark, cavernous interior.The Kryptonian Fortress, it is dark in color and they (or at least the cave) glows red in the darkness.
Exterior Design: The Fortress is planted outside somewhere in the Desert and is held up by many huge desert-like columns. From far away, its full structure and design can be fully seen. The crystalline structure of its buildings and crisscrossing crystal towers.