Control Spire

Description
Control Spires (Dark Towers in the original Japanese version), are dark obelisk towers created by Ken Ichijouji, under the influence of a Dark Spore as the Digimon Emperor. They feature prominently in many episodes of Digimon Adventure 02. The Control Spires prevent natural Digivolution, rendering the Digimon unable to evolve normally. They also work in conjunction with the Dark Rings to control Digimon.

They are also used to mark territory of the Digital World that was under the control of the Emperor. They are unable to prevent Armor Digivolution. Armor Digivolution was created when the Sovereigns used the Crests of the previous DigiDestined to form a protective layer over the Digital world. Around the same time, the Sovereigns were released after being sealed by the Dark Masters. Before the events of Digimon Adventure 02, the Soverigns were sealed again, this time by the Control Spires. The Soverigns created the Digi-Eggs, using the Crests as a template, as a way to override the Control Spires and give the new group of Digidestined the power to defeat the Digimon Emperor.

It is unknown how the Control Spires are created, and if the Digimon Emperor was the first one to create them. Ken later notes that he cannot remember how he made the Control Spires during his reign as the Emperor.

When a Control Spire is destroyed, normal evolution can be achieved. As well, that territory is removed from the Emperor's control and the Dark Rings become useless.

Several spires and rogue Digimon were later found in the Real World during the Digimon World Tour arc, that terrorized humans around the world.

Control Spire Digimon
Arukenimon and Mummymon later began turning these Control Spires into Digimon. 1 Control Spire was used to create Golemon, 50 for Okuwamon, and 100 to create BlackWarGreymon. It seems that 1 Control Spire would create a Digimon of the Champion level, 10 an Ultimate, and 100 a Mega. Other Digimon regard these creatures as "fake", and reveal a dark body resembling the Digimon when damaged. Both Golemon and Okuwamon were defeated by the DigiDestined, while BlackWarGreymon felt his creators were inferior to him and went to find himself, before later being destroyed by Oikawa.