Serpent Citadel
The Serpent Citadel is the secret headquarters of The Serpent Society.
History
Concept and Creation

The Serpent Citadel was created by Julian Penrod of West Orange, New Jersey from a comic book fan contest, "Serpent HQ", that was first advertised in the letter column of Captain America #315 - The Hard Sell to be the secret headquarters of The Serpent Society. Julian's suggestion was announced as the winner in the letter column of Captain America #322 - The Chasm:
"An abandoned hospital for the criminally insane, which would have the medical facilities for bionic grafting done to various members, private rooms, and the shock treatment device Sidewinder used on Princess Python, located in upper New York State..."
While the Serpent Citadel was mostly first shown as a undisclosed location since the Serpent Society's comic book debut, the official physical appearance of the Serpent Citadel appeared in The Official Handbook of the Marvel Universe #11 - S-U: Subterraneans to Ursa Major and in Captain America #341 - Break-In; Free Speech; In Our Midst!., where Viper enacts a coup d'état on Sidewinder's Serpent Society from within by her sleeper agents.