Arch-Builders

The Arch-Builders are an extinct alien civilization associated with the planet Ozymandias. They have been extinct for approximately forty-three hundred years. When Hadrian first learns that the alien ruins at Calagah on Emesh predate human settlement by thousands of years, the Arch-Builders are the first known extinct alien civilization he thinks to compare them to — but Valka confirms the Calagah ruins are far older than the Arch-Builders, placing the civilization that built them in a more ancient and less understood category.