Plumber Headquarters

The Plumber Headquarters is a location that appears in Ben 10: Alien Swarm and Ben 10: Omniverse. It is a functional Plumber Base, led by the Magister of Earth, Max Tennyson. One of the known entrances is through the Max's Plumbing shop bathroom till the base was moved to the orbit.

Alien Force
It was first seen in Ben 10: Alien Swarm, when Ben went to Grandpa Max to ask about the Nanochips.

Omniverse
It re-appeared in The More Things Change: Part 1, when Ben visited his grandfather, Max.

In Trouble Helix, Ben was training with Blukic and Driba. Khyber infiltrated the base to get informations about Ben and Malware.

In It Was Them, Rook and Ben checked Dr. Animo's cell.

In Outbreak, It was invaded by Dr. Psychobos and his robots. After the Omnitrix malfunctioned, some prisoners were transformed into some of Ben's aliens. The prisoners tried to escape from the prison, but were defeated by Ben, Rook and their team and were sent back to their cells.

Ben 10: Alien Force

 * Ben 10: Alien Swarm (first appearance)

Ben 10: Omniverse

 * The More Things Change: Part 1 (first re-appearance)
 * The More Things Change: Part 2
 * A Jolt from the Past
 * Trouble Helix
 * Have I Got a Deal for You
 * It Was Them
 * So Long, and Thanks for All the Smoothies
 * Of Predators and Prey: Part 1
 * Outbreak
 * Blukic and Driba Go to Mr. Smoothy's
 * Arrested Development
 * Ben Again
 * Store 23
 * Showdown: Part 2
 * The Frogs of War: Part 1
 * The Frogs of War: Part 2
 * Rad
 * Evil's Encore
 * Food Around the Corner
 * Mud Is Thicker Than Water
 * The Ultimate Heist
 * Max's Monster
 * Something Zombozo This Way Comes
 * Animo Crackers
 * Catfight
 * The Rooters of All Evil
 * Universe vs. Tennyson
 * Clyde Five
 * Rook Tales
 * Breakpoint
 * Color of Monkey
 * Stuck on You
 * Final Countdown
 * Malgax Attacks
 * The Most Dangerous Game Show
 * The End of an Era (future)
 * A New Dawn (future)

Trivia

 * The Plumber Headquarters' design is similar to the "Prison 42" from the TV show The Avengers: Earth's Mightiest Heroes.
 * When the Plumber Headquarters was sent into space, its exterior looks similar to the Justice League Tower.