Mr. X's Castle

Mr. X's Castle, known as the X Foundation Headquarters (エックス財団本部ビル) in Japan, is the fortress used by "Mr. X" in Mega Man 6 and the location of the four Mr. X Stages (Mr.Xステージ). Mr. X's Castle consists of four parts, each part being a level Mega Man must go through. The same song plays for all Mr. X Stages. The final part of the fortress ends with a battle between Mega Man and Mr. X.

Mr. X Stage 1
The first level in the series of Mr. X Stages. Mega Man begins outside of the castle, attempting to break inside. A lot of the level involves climbing upward, avoiding spikes and an abundance of Cannopellers.

Enemies

 * Batabattan
 * Cannopeller
 * Cyber Gabyoall
 * Hotchkiss'n
 * Skull Walker
 * Tatebo
 * Wall Blaster 2
 * Boss: Rounder II

Mr. X Stage 2
The second Mr. X stage. It has a space feel, with large windows that give the player a view of the night sky. The level contains a large amount of Mets, as well as Skull Walkers in the later parts of the stage. There is also no vertical scrolling at all, making this level like a hallway of the fortress.

Enemies

 * Hotchkiss'n
 * Metall
 * Molier
 * Skull Walker
 * Boss: Power Piston

Mr. X Stage 3
The third Mr. X stage, a boiler area.

Enemies

 * Ben K
 * Cannopeller
 * Cyber Gabyoall
 * Fire Telly
 * Pooker
 * Boss: Metonger Z

Mr. X Stage 4
The fourth and last Mr. X stage, an area that seems to be used for robot production.

Enemies

 * Colton
 * Peat
 * Shield Attacker GTR
 * SW-525
 * Tadahou
 * Wall Blaster 2
 * Boss: X Crusher

Other media
In the Rockman 6 manga, the X Foundation Headquarters is located in the center of a giant flying city named New Metropolis (ニューメトロポリス) that is hidden in space. When Mr. X's eight robots are defeated, New Metropolis descends and attacks a city with its weaponry. Mega Man invades New Metropolis and fights against its defenses, including Rounder II, an army of Mets, Power Piston and Metonger Z.

When Mega Man destroys the X Crusher, Mr. X reveals he is Dr. Wily and escapes, setting the New Metropolis to fall on the city. To save everyone, Mega Man rushes to the city's control room, but to his surprise, New Metropolis stops falling and goes up. When he enters the control room, Mega Man sees the Metall that was piloting Metonger Z, who stopped the fall and sacrifices himself by taking New Metropolis high in the sky and exploding it after Mega Man leaves with the Jet Adaptor.