Constructed by the same civilization that built the Spires, the Oldwalls are massive stone walls that stretch across all of Terratus. Built from weathered stone, the Oldwalls tower above the land, visible for miles in every direction. Only the Spires reach taller than the Oldwalls. Notably, both exist across the whole of the Overlord's dominion. Dozens of them, jutting up from the lands and grasping at the sky. They can certainly be toppled; there are a handful of ruined Spires in the empire. Terratus has changed since they were constructed - some Spires have been swallowed by the mountains, others by the seas. There's one sticking out of the water off the coast of the islands due north of the Bastard Tier, for example.
By Kyros' law, the Oldwalls are forbidden. Where there are Oldwalls, there are Bane. No one knows why the magical creatures are attracted to the Oldwalls, but every traveler who strays too near the walls is attacked. Very few who have attempted to enter the Oldwalls ever return alive.