Beyond the Phlogiston

THE CITADEL on astronomical object at 09^h 50^m 57^s   −56° 26′ orbiting planetesimals in the Northern Local Supervoid which separates the Northern Local Void from the Boötes Void

Inhabited by a host of whatever species can subsist within the limited atmosphere of the gas pocket left by the dead planet detritus and automated systems whose only directive is to identify and exploit whatever resources discovered. The Citadel predates the exploratory adventurers who now inhabit it.