Mt. Rushmore

The Mount Rushmore National Memorial (often referred to as Mt. Rushmore) is a location on Earth that was used as a Plumbers base.

Ben 10
In the original series Season 1 finale, it was revealed to be a Plumbers base by Max. It was shown to have multiple pieces of technology, including an arsenal of heavy weapons, all of which could be accessed by pulling open different drawers. This technology was used to enter Vilgax's ship and rescue Ben.

In Truth it was visited by Phil so he could steal the Null Void Projector. This was because he was making money off of his so-called "heroics," (saving people's lives from aliens), but he was actually releasing them so he could earn money. He, however, was stopped by Ben, Gwen and Max and sent into the Null Void.

In Ben 10 vs. the Negative 10, Mount Rushmore was seen, however only the outer location was seen at the end of part 1. In part 2 the Tennysons tried but failed to prevent them from breaching the stronghold. They battled inside the room with the Sub Energy but though they defeated and trapped 8 of the Negative 10 members they failed to protect the sub energy. However Perk Upchuck stopped the Forever King by swallowing the energy and making a powerful blast. However this destroyed Mount. Rushmore and a hologram was used to prevent anyone from seeing the damages.

Ben 10: Protector of Earth (Alternate Timeline)
It was a level in the video game Ben 10: Protector of Earth

Ben 10: Alien Force
In War of the Worlds: Part 1 the team briefly visited the mountain to free Darkstar from the Null Void.

Ben 10: Ultimate Alien
It was revealed that over the course of the original series, Alien Force and Ultimate Alien it was repaired (likely by the Plumbers). However it was damaged again by Lucubra Vilgax (by ripping off George Washington's face to break into the base) and the Esoterica. It is unknown if it was repaired after this.

Ben 10: Omniverse
It was revealed that Mt. Rushmore became a fully functioning Plumber base when Ben was 11 years old. In Malefactor, it was used to keep a Psycholeopterran safe. Later in the episode, it was attacked by Malware while Khyber took DNA sample from the smuggled Psycholeopterran.

In Evil's Encore, five years before Omniverse, Dr. Animo took control of the base and tried to use the Plumber satellite network to spread his mutation ray over the Earth. He was stopped by 11-year-old Ben, Gwen and Max Tennysen.

Notable Pieces of Technology

 * Null Void Projector
 * Tachyon Cannon
 * Other Various Pieces of Alien Tech

Ben 10

 * Secrets (first appearance)
 * Truth
 * Ben 10 vs. the Negative 10: Part 1
 * Ben 10 vs. the Negative 10: Part 2 (damaged and mostly destroyed)

Ben 10: Alien Force

 * War of the Worlds: Part 1

Ben 10: Ultimate Alien

 * The Ultimate Enemy: Part 2 (first reappearance) (damaged)

Ben 10: Omniverse

 * Malefactor (first re-appearance) (flashback)
 * Evil's Encore (destroyed)