The base of operation for both the X-Men and it's sister team, the New Mutants, is the Xavier Mansion at 1407 Graymalkin Lane in the town of Salem Center in New York State's Westchester County. The mansion belongs to the founder of both teams, Professor Charles Xavier, and has been in his family's possession for ten generations. The mansions was originally built by a Dutch seafaring ancestor of Xavier's out of local stone on the edge of Breakstone Lake. Ove the years the mansion has been electrified, renovated, and modernized. Many of the renovations involved the installation and construction of facilities for use by the X-Men, including the addition of the subterraneam hangar building, the Danger Room and its equipment, and the high speed transport tunnels. (The Danger Room is the area in which the X-Men and New Mutants are trained in the use of their superhuman powers.) The mansion was destroyed in an attack by Sidrian Hunters, but was rebuilt incorporating advanced Shi'ar technology provided by Lilandra Neramani, who was then the empress of the Shi'ar. The general populace is unaware that the mansion serves as the headquaters of the X-Men and New Mutants. Instead, the mansion is publicly known as the lacation of Professor Xavier's Shool for Gifted Youngsters, a respected private school with a highly limited enrollment. During Charles Xavier's current absence, the school is headed by the mutant Magneto, under his adopted identity of Michael Xavier, Charles's supposed brother. All of the school's students are secretly member of the X-Men and New Mutants.

Charles Xavier's estate covers an extensive area between Graymalkin Lane and Breakstone Lake. There is an Olimpic-size swimming pool directly to the rear of the mansion. Elsewhere on the property there are stables and a boathouse. Hangars and a takeoff pad for the X-Men's "Blackbird" jet are located in an area of the estate far away from public view. These facilities may be reached from the mansion by means of high-speed magnetic rail cars the travel through an underground tunnel.

ATTIC
The attic of the Xavier mansion is primarily used as a storage area. However, one large room on the level is used by the X-Men's leader, Ororo Munroe, alias Storm, as her living quarters. Storm prefers this spacious attic room to the smaller rooms occupied by her fellow X-Men. "Ororo's Roost" contains her sizable collection of plants, which receive sunlight from the large overhanging skylight. The attic also has a large "playroom," used as a recreation area, a room for communications equipment, and the stairway up to the mansion's cupola.

SECOND FLOOR
Apart from Storm, all of th X-Men and New Mutants have their private living quarters on the mansion's second floor. Professor Charles Xavier's living quarters are on both the first and second floor; his bedroom is on the second. During Charles Xavier's absent, his living quarters were occupied by Magneto, the former head of Xavier's school mutants. The X-Men occupy the rooms on the second floor in one wing; the New Mutants occupied the second floor in the opposite wing. The New Mutant Magik and the X-Man Shadowcat share the same room. Former staff members Thomas Corsi and Sharon Friedlander also previously lived on this floor. The most frequent occupant on the second floor's guest rooms is Xavier's colleague Dr. Moira MacTaggart. The second floor also holds laundry facilities, a workshop, and a recreation area.

FIRST FLOOR
The main entrance to Xavier's mansion is on the first floor, as well as a back enterance that the residents use for access to the swimming pool and much of the rest of the estate. There are numerous surveillance and security system on the first floor (as thereare, to a lesser extent, on the other floors and throughout the estate) to alert the residents to the presence of any visitors or intruders. The first floor contains a magnificently furnish living room and main dining room, as well as a more informal dining room, used for breakfasts and lunches, and a casual sitting room, often used by visitors to the school. Charles Xavier has private living quaters on this floor as well as the second; also, on the first floor he has his study, where the principal terminal of hisCerebro machine is located, his office, from which he conducts school business, and an enormous library, where most of the school's classes are held. All of Xavier's rooms were being used by Magneto while he was in charge. the first floor also holds the mansion's main computer and kitchen facilities.

BASEMENT
For the most part the first sub-surface level of the Xavier mansion serves the normal function of a basement; it contains the oil heater and water heater and is used for the storage of wine, furniture, and books. The basement is also the location of the mansion's auxiliary generator. The main memory components of the mansion's computer system are also located here, however, and there is an enterance to a secret passageway leading to the lower levels.

SUB-BASEMENT LEVEL ONE
The Xavier mansion's Sub-Basements were constructed only in recent years. Sub-Basement Level One is primarily given over to extensive medical facilities, including a fully equipped operating room that can hold twenty-five beds for patients without crowding. This level also includes a fully-equipped gymnasium, an indoor Olympic-size swimming pool for use when it is too cold to use the outdoor pool, a sauna and steambath. Locker rooms are also located on this level. Sub-Basement Level One also contains various laboratory facilities and the terminal for the high speed magnetic rail cars that are used to reach the hangars through an underground tunnel.

SUB-BASEMENT LEVEL TWO
During th recent rebuilding of the Xavier mansion, most of the new Shi'ar technology was installed on Sub-Basement Level Two. Most of this level is devoted to the Danger Room facilities. The origanal Danger Room, where Xavier trained mutants in the use of their powers, was on the mansion's first floor and employed advanced techology designed on Earth, even encluded robots. The current Danger Room instead employs Shi'ar technology, including extraordinary sophisticated holographic projectors. Virtually any enviroment can be duplicated within the new Danger Room by means of Shi'ar techology. X-Men and New Mutants training there may be pitted against formidable opponents that are actually either holograms or highly advanced robots, both created by Shi'ar means. This Sub-Basement also includes alternate living quarters and other facilities for use in emergencies.