Located at 1407 Graymalkin Lane, just outside of Salem Center, Westchester County, New York, the original ancestral Xavier estate was built in the late 1700s. Currently owned by Charles Xavier, this sprawling mansion was erected near Breakstone lake and serves as a school, as well as the secret headquarters of an elite team of mutants known as the X-Men.
The estate was originally named The Xavier School For Gifted Youngsters, but changed its name to The Xavier Institute for Higher Learning with the opening of a new school in Snow Valley, Massachusetts. Since the recent closing of the Massachusetts Academy, the original name was restored, although due to the reconstruction of the Mansion the name has once more been changed to The Xavier Institute for Higher Learning.
The Mansion was destroyed by a brainwashed Franklin Richards, a student at Xavier's. During its reconstruction, the Mansion took on a bold new appearance; the overall Mansion is in the shape of an "X", while it boasts two separate dorm buildings and a maze.
Although the outside looks modern, the inside has retained its 1700s-style decor with oak-paneled walls and wooden floors. The mansion still houses its state of the art facilities for the education, training and protection of mutants.
The X-Mansion was renamed from Xavier's School for Gifted Youngsters to the Xavier Institute for Higher Learning, as most of the X-Men were adults rather than teenagers by this time. Xavier's School for Gifted Youngsters was relocated to the Massachusetts Academy in Boston, Massachusetts, which served as the training site of the third generation of teenage X-Men, Generation X.
Some years later, the Massachusetts Academy closed permanently.  The school for young mutants was moved back to the X-Mansion, but the name Xavier's School for Gifted Youngsters was no longer used at all. fourth generation of mutant teenagers were taught at the Xavier Institute for Higher Learning at the X-Mansion.
Though protected by high-tech defenses, the X-Mansion was often breached by the supervillains and evil mutants faced by the X-Men. Indeed, the X-Mansion was destroyed and rebuilt several times. It was destroyed by the Sidri and again by Mister Sinister. However, certain portions of the mansion, such as sub-basements, survived both attacks. During Operation: Zero Tolerance, Bastion forced Jubilee to reveal the mansion's defenses. He then stripped down the mansion, having nearly everything inside the mansion removed. After defeating Bastion, the X-Men moved back into the mansion and restocked it. Most recently, the X-Mansion survived an assault by the Shi'ar Imperial Guard as well as a riot by students led by Quentin Quire. In the wake of M-Day, the mansion was infiltrated by followers of the Reverend William Stryker in an attempt to wipe out the students, resulting in some structural damage. Lastly, an attack from a group of Sentinels destroyed the X-Mansion one last time. This time, though, the X-Men decided not to rebuild it, instead relocating to San Francisco, California.
Blueprints for the newly-rebuilt mansion were given in Official Handbook of the Marvel Universe: X-Men 2004.
The X-Mansion is now in the shape of an X. In the middle of the main courtyard is the Phoenix Memorial Statue, dedicated to the memory of Phoenix. Notable rooms include the Danger Room and a room containing Cerebro. The Headmaster's Office of Cyclops and Emma Frost is on the top floor. The basketball court is a popular hang-out; it was the site of a well-known basketball game in which the X-Men used their mutant powers. Directly below the basketball court is the hangar, which houses many transportation vehicles, as well as aircraft such as the X-Men Blackbird.
A large tiled courtyard leads to the main entrance of the Mansion.
A large, plush foyer splinters off into various rooms, and straight through the foyer leads to the hyperlift, an elevator that leads to the Restricted Access Sub-Levels and the Administration Wing where the offices of the Student Dean, Headmaster, and Administrator are located.
Access to the back is gained through various points, the main entrance being the kitchen. Located at the rear of the estate is an Olympic-sized swimming pool, basketball court and main entrance to Breakstone Lake. Each of these facilities are for students, faculty and X-Men.
Devil's Rock used to be the exit and entry point for the X-Men's aircraft, the Blackbird, but since the Mansion's reconstruction, it has been relocated beneath the basketball court. Upon departure and landing, a klaxon will sound warning for anyone nearby to vacate the area. Students are advised to move immediately once the klaxon sounds.
Located behind the large maze is the Girl's Dorm Building, and located behind the 'center tower' of the Mansion is the Boy's Dorm Building.
To the East of the Mansion is the maze, and to the West the full-sized baseball diamond, complete with spectator stands, scoreboards and commentator stand.
Classrooms, canteen, and library are all located in the "center tower" of the mansion.
Scattered throughout the ground floor are various rooms and halls, such as a large ballroom that occupies the domed structure near the rear of the building, the students' recreation room, and various other game and computer rooms.
Also located on the ground floor is the nurse's office, which is a ground-level medical lab which anyone can access. It is run by either the medical staff of Xavier's, or RALPH, the holographic doctor.
Forests, farmland, and lakefront surround and isolate the entire estate for miles. The nearest town is Salem Center.
This floor is dedicated mainly to the quarters of faculty, staff and X-Men. Aside from the quarters, there are laundry facilities, a workshop, and a recreation area that is strictly for faculty, staff and X-Men.
Adorning the top of the mansion is a large glass-paneled dome. Because Storm prefers this spacious attic room it has been adapted to her use. It is filled with various types of plants, much like a greenhouse.
In addition to the campus grounds, the Xavier Institute also houses an array of restricted access Sub-Levels. In the sub-levels you will find The Danger Room, War Room, Hangar Bay, holding cells, research and development labs, medical labs and Cerebra chamber.
Voice-activated hallway icons give interactive directions through the sub-levels, though these are restricted to the sub-levels.
Access to the sub-levels is only available to faculty, X-Men, and students -- although students are only granted access once they have spoken to their squad leader or faculty advisor.
To access the sub-levels you must go to the hyperlift at the end of the hallway in the foyer, then proceed through the various security measures such as hand scans, retina scans, voice scans and passcodes.
The Danger Room consists of two parts, the Danger Room itself, and the Control Room which is housed above the Danger Room. To the untrained eye, the Danger Room is a featureless room. To those who are (un)fortunate enough to engage its systems, it is the ultimate battle simulator. It employs highly advanced technologies from sources such as the Shi'ar, Forge and Beast.
The Danger Room pits its opponents against an array of physical and holographic opponents that tests a trainees' mastery over their mutant powers to peak endurance.
Using the advanced technologies, the Danger Room can give the illusion of being many times bigger than it actually is. Anything from gravity, heat, humidity, or texture can be manipulated from the control booth.
Students are not permitted to be in the Danger Room unless accompanied by an instructor or X-Man.
To most people, it's a big, round room. To those who actually know what it is, it is no less than amazing. The Cerebra chamber houses Cerebra, a mutant locating and telepathic ability amplifier. When a telepath uses Cerebra, their telepathic abilities are boosted to an incredible degree. It is usually used for scanning for new mutants, but it can be used for other purposes.
A non-telepath can also use the Cerebra machine, although this is not recommended unless they are trained because they may experience various degrees of psychic trauma.
The holding cells are an underground storage facility for those villains that the X-Men deem too unsafe to let roam about freely. The holding cells consist of small titanium-steel cells with the same type of door. Various safety measures can be taken such as erecting an internal force field to back up the titanium-steel walls, a nullification field to 'switch off' mutant abilities, and various other precautions. There are also stasis tubes which hold inhabitants in a state of suspended animation until they are awakened.
The War Room is located near the Danger Room. It is the 'operating center' of the X-Men. This is where briefings are given, missions are planned, and meetings take place.
There are various computers and monitors around the War Room, each with their own function. The War Room monitors news feeds from every news network on television and radio, and scans every known frequency for reports on events occurring around the world. Thanks to the artificially intelligent computer program Cerebra running throughout the mansion, the X-Men don't need to scan 24/7. If Cerebra picks up something, it will notify the X-Men through their communication links.
These labs are usually used by Dr. Henry McCoy and other medically-trained mansion staff. RALPH, the holographic doctor is also installed in the lower-level Medical Lab in the event that Dr. McCoy or another member of the medical team is unavailable. When Team Marvel stripped the Mansion of its technology. Dr. McCoy had to reinstall it all, making a few modifications along the way. His own personal lab and the medical lab are now equipped with tele-immersive displays.
This is one of the very few places on the Estate that is actually as it seems. The Hangar Bay is just that, an underground area for the storage of the X-Men's aircraft, notably the Blackbird. The exit and entry point has been relocated. Prior to reconstruction, it was located at Devil's Rock, but now it is located beneath the basketball court. A klaxon will sound to warn anyone nearby to evacuate the area. Students, faculty, and X-Men are advised to move immediately.
On the off-chance that the Mansion is invaded, there is an access hatch to the Morlock Tunnels in the sub-levels. This is only to be used in an all-out invasion or attack. Students are to be lead out first by a member of staff, followed by other staff and faculty members, and, if necessary, the X-Men.
In Mimic of the Exiles' home reality, the school looks more spanish style, though it is still located in New York State. Residents included The X-Men, (Charles Xavier, Scott Summers, Jean Grey, Hank McCoy, Bobby Drake, Calvin Rankin, Ororo Munroe, Piotr Rasputin, Kitty Pryde, Kurt Wagner, James Howlett, and an Unknown mutant).
Blown up by the government in an attempt to rid the world of Mutants. Magneto knew it was going to happen, and didn't stop the humans, but instead used the attack as an excuse to rid the entire planet of Human life by crashing a meteor into it.
In Earth-311, the year is 1602, and the School for Gifted Youngsters is reimagined as Carolus [sic] Javier's Select College for the Sons of Gentlefolk. The college is a haven, set up by Carlos Javier (1602's Charles Xavier) for the 'witchbreed' (the mutants of this reality). It is located in Warwick, England. Carlos resides at the college with his students: Scotius Sumerisle (the captain of the team), Roberto Trefusis, Werner, Hal McCoy, and Javier's page John Grey. Javier has good relations with Queen Elizabeth and her spymaster, Sir Nicholas Fury, and it is revealed (in Part Two) that the students are "refugees and orphans" that Elizabeth allowed into England to escape persecution elsewhere (indeed, Werner was saved in Part One from being burned at the stake by the Inquisition in Domdaniel).
Although there is no 1602 equivalent of the Danger Room, Javier does briefly dream of "a room in which dangers would come from nowhere", to teach his pupils to fight like a team.
When Elizabeth dies and James VI of Scotland becomes King of England as well, he sends Fury to close the school and take all its residents prisoner. On Fury's advice, Javier and his students surrender peacefully, although they later escape custody and flee to Roanoke colony in America.
On Earth-12, the X-Men still operate out of the School. Blink returned Mimic's body there when the Exiles began sending bodies from the Stasis Wall home.