Robotnik's Headquarters

Robotnik's Headquarters is an egg-shaped citadel that served as the main base of operations for it's evil architect Doctor Ivo "Eggman" Robotnik and his empire and it is located in the center of the industrial city of Robotropolis. It is a location in the Sonic the Hedgehog universe including the Archie comic book series ofSonic the Hedgehog.

Formerly it was Castle Acorn, the royal palace that was the seat of power for the Kingdom of Acorn. But after the despotic mad genius' coup, the entire castle along with the rest of Mobotropolis were undergoing technoformation (also referred to as "cybermerging") and changed into a polluted industrial wasteland. Dr. Robotnik's mechanical pet Cluck and his conniving nephew Snively took residence within the headquarters with Robotnik. The building where Robotnik used the infamous Roboticizer to roboticized all citizens of Mobotropolis into his mindless slaves.

After Operation: EndGame, the House of Acorn retook the castle back and stated to change it back to it's old carnation before Robotnik's coup. Unfortuanitly Mobotropolis was retaken by Dr. Eggman, though the HQ was destroyed along with the rest of the city by nukes from Station Square.

Appearances in other media
Robotnik's Headquarters made an appearance in both cartoon shows Sonic the Hedgehog (SatAM) and Sonic Underground.