Layout of Enerjak's new citadel.
The Citadel of Darkness was the heart and center of Enerjak's city of Nekronopolis. An ugly, nightmarish and foreboding spire, it reflected the corrupted views of Dimitri when he tried to take over Angel Island roughly 400 years ago (around year 2835) after his transformation. Modeled after the Dark Tower he erected which became Mount Fate centuries ago, it was strategically located where the Hall of Learning was in the former site of Echidnaopolis. The citadel had multiple levels with its own environmental control and facilities for Enerjak's followers, as well as an overlook and entrance hall. The ground floor was where Knuckles the Echidna and Archimedes battled and defeated the Chaotix after barely escaping the city's Mechanaut force. Enerjak then subdued the two and brought them to the highest level of the citadel where he and Knuckles engaged in hand-to-hand combat. Archimedes, in the meantime, contacted more of his fellow fire ants who gathered to eat out the foundation of the building's top floor. At the same time, Locke sent a series of remote-controlled rocket booster modules from Haven to attach to the uppermost level of the citadel which then activated. Between the assistance of both parties, Knuckles and Archimedes managed to narrowly escape through a hole in the citadel's floor as the boosters carried it and Enerjak into space and a low-level orbit around Mobius. With Enerjak gone, the rest of the citadel as well as Nekronopolis, vanished into thin air. (KMS: #3)
The citadel portion that was in space became Enerjak's new prison until he was summoned back to the planet by Mammoth Mogul, although why he could not return on his own is a mystery. (KtE: #7)