Final Egg

The Final Egg (ファイナルエッグ) is a location that appears in the anime series Sonic X. It was Dr. Eggman's hidden base in the Mystic Ruins until its destruction. As a part of its defenses, it was ridden with several traps made specifically for Sonic.

Chaos Saga
Having been built in secrecy, the Final Egg was discovered by Sonic when he chased Dr. Eggman through the Mystic Ruins. Seeking Eggman, Sonic broke into the Final Egg, prompting Eggman to unleash all the traps in his base against him, including lasers, corridors covered in rolling bars to neutralize Sonic's speed, and a giant ball for flattening Sonic. However, Sonic got past all of them.

Having Bokkun deliver a live-feed message to Sonic, Eggman challenged Sonic to a final battle in the deepest section of the Final Egg. There, Eggman fought Sonic with his Egg Viper which Sonic defeated after grueling battle, causing a chain reaction that made the Final Egg explode while Sonic and Eggman fled.

Trivia

 * Although it retains most of its game counterpart's interior design, the Final Egg is a hidden base rather than a base in the wide open. It is also not a tower, but more of a dungeon.