'The House' is a domain that serves as the center of the universe in the Keys to the Kingdom series by Australian author Garth Nix. Anything in creation not in the House, such as earth (the solar system and indeed this universe), is part of the Secondary Realms. The House is divided into seven demesnes; each of which is ruled by a master named for a day of the week, the Trustees, or sometimes the Morrow Days. The demesnes are, in the order Arthur Penhaligon has claimed them: the Lower House, the Far Reaches, the Border Sea, the Great Maze, the Middle House, the Upper House and the Incomparable Gardens.

==Description==
The House's physical appearance in the Secondary Realms is described as a vast building featuring many different architectural styles, which often appear to be brought together at random. Its physical location differs; Arthur first sees it near his own residence, and his friend Leaf sees it above a hospital. Arthur, Leaf, and Leaf's ally Sylvie are the only mortals shown to see the House, each by a different means: Arthur can see it presumably because he is the Heir of the Architect; Sylvie requires special glasses given to Leaf by the House Sorcerer Dr. Scamandros; and Leaf appears able to see it without aid. It is her belief that she has inherited powers of extrasensory perception from her grandmother, whom she thinks to have been a witch, but this has not been confirmed. A possible alternative suggests that her immersion in the House (which occurred prior to her view of it from outside) enabled her to see it.

The House has seven demesnes: the Lower House, Far Reaches, Border Sea, Great Maze, Middle House, Upper House, and the Incomparable Gardens. The Gardens are the uppermost part of the House. The Lower Coal Cellar can be acted as the basement, and it is infinite.

==Purpose==
The divine figure known as the Architect created the House to record, without intervening on any behalf, all that happened in the Secondary Realms (a term used to describe the Universe at large). Most Denizens of the House believe that the House was created first. Having created House, Realms, and a Law that would prevent Denizens from intervening in the actions of mortal creatures, the Architect vanished and is not shown again. The Law is not binding however (although in Grim Tuesday, Arthur repels two agents from the House by invoking the Original Law, along with his latent power gained from the use of the First Key); it can be broken, as all of the Architect's Trustees have done at one time or another, making themselves the villains of the story. A Trustee can only enter the Secondary Realms on their "day", e.g. Mister Monday can only enter the Secondary Realms on a Monday. Furthermore, the Superior Denizens (Dawn, Noon, and Dusk) of each day can only enter the Secondary Realms on the hour of their name (a Noon, for example, can only enter during the hour from 12:00pm to 1:00pm).

House Time is constant, while time in the Secondary Realms is malleable; it is even able to flow backwards if a sufficient power, such as a Key to the Kingdom, is used upon it. Thus, a day may pass on Earth while half a year will pass in the House. This inconsistency in time allows Arthur to spend large amounts of time in the House whilst 'Local Earth Arthur time' remains still. This occurs because the Front Door (the main method of transit between the House and the Secondary Realms) takes note of important people's travel (e.g. Arthur's passage through the Door) and alters the time it allows passage back accordingly. The system is not infallible; while Leaf is in the House, time continues as normal in the Realms (Sneezer states that the Door did not consider Leaf noteworthy enough to account for). This temporal system is not dissimilar to that used in the Chronicles of Narnia, wherein lengthy adventures or even lifetimes can be spent in Narnia's world while only seconds pass in ours.

==Denizens==
Denizens are the original inhabitants of the House. Denizens are ranked within the House in an order of Precedence, but the current hierarchy of ranking is unknown. A Denizen's social status, political role, and magical power appear to be synonymous, in that magical power over an item is given or taken in the same way as if it were political power.

Denizens are similar to humans in all aspects but these:
* The blood of a Denizen is blue with two unexplained exceptions, while the bones are golden.
* Denizens are very resistant to change of any kind, and are often described as narrow-minded or stupid.
* Denizens are naturally good-looking. Additionally, if a Denizen’s House Precedence is high, he or she is better-looking and taller than Denizens of lower precedence.
* Denizens are nearly immortal:
**Denizens cannot die of old age, sickness, dehydration, or starvation while in the House, and will eventually heal from almost any injury, including decapitation. Denizens normally value sicknesses from the Secondary Realms. If the body is destroyed, they can slowly grow a new one, though they can be prevented from doing so. The ability to survive without food or drink while within the House, as well as not dying from old age, extends to Mortals and Piper's Children, although the resistance to injury does not.
**Denizens can only be killed by
***Fire, superheated steam, or other sources of extreme heat;
***Certain weapons (such as the Commissionaires’ Clubs and various weapons used by the Glorious Army of the Architect);
***A prolonged absence of their heads; without sorcerous intervention
**Nothing
***A festering bite or scratch from a Nithling, which dissolves them into Nothing;
***A Key;
***Drowning (although, this does not completely kill them immediately); and
***Falling from at least 15,000 feet.

==Demesnes==

===The Lower House===
The Lower House was the domain of Mister Monday. Due to Monday's affliction with sloth, its bureaucratic affairs became impossibly inefficient until Monday's loss of power, after which Dame Primus, as the Steward of Arthur's regime, has attempted to make the Lower House manageable. The remaining Morrow Days have attempted to impede this effort by swamping the Lower House with paperwork.

Doorstop Hill, and on it the Front Door of the House, is located in the Lower House. The Front Door of the House is a means by which one may leave the House and enter a Secondary Realm, and vice versa. To enter it from the Secondary Realms, one must be able to see the House. It is a pair of wooden doors surrounded by constantly shifting wrought-iron patterns whose movements are mesmerizing to human eyes. The Door is guarded by the Captain Keeper; in his absence, the Lieutenant Keeper of the Door, an ally of Arthur's, has guarded it ever since.

The Coal Cellar is a deep pit in the Lower House where Denizens that have been punished are sent to mine and shape coal for delivery to buyers within the House.

The Seven Dials is a set of seven grandfather clocks in a room accessible from Monday's Dayroom, the main office of the Lower House. Using them, one can travel to the current time in any given Secondary Realm. Thus far, only Sneezer, Monday's butler, has operated them.

===The Far Reaches===
The Far Reaches was the domain of Grim Tuesday. Originally, the Far Reaches was a Grand Cavern, and in the Cavern was a steady spring of Nothing. Tuesday used the Nothing to create items, such as Commissionaires and Not-Horses, which he sold to other demesnes of the House. His avarice, however, drove him to deepen and widen the spring in an effort to find more Nothing. In time, the spring became a vast Pit, which eventually becomes the whole of his demesne, sparing only his Treasure Pyramid and the train station where his personal train into the Pit docks. Grim Tuesday used indentured slaves from his own demesne, as well as ones from other Morrow Days sent to him as payment, to mine the useful amounts of Nothing. The Pit is extremely dangerous as it has been dug deep into the foundations of the House and is very close to breaching into the void of Nothing beyond.

===The Border Sea===
The Border Sea was an ocean previously under the rule of Drowned Wednesday. After Wednesday transformed into a leviathan and submerged into the sea, the sea overflowed nine-tenths of all land in the demesne including Port Wednesday. A new port was partially prepared on Wednesday's Lookout before this deluge. Any of the buildings that were submerged were transformed into ships, which thereafter sailed the Border Sea along with Wednesday’s original fleet of 49 ships. A unique aspect of the Border Sea is that anything that is lost accidentally, but not stolen, will appear in it.

The Border Sea extends into any body of water in the Secondary Realms, and therefore can be a means of travelling anywhere. The Line of Storms, a series of vicious lightning storms, guard the entrance into the sea; only an express invitation into the Sea will prevent the Line from killing people instantly.

Raised Rats live here and pilot their steamships. Pirates also live here, of whom the most formidable was a mortal pirate who somehow passed the Line of Storms into the Border Sea, Elishar Feverfew. Feverfew was a trained House sorcerer, and was trained in several dark arts. He used Nothing very indiscriminately and had been changed by this Nothing into something not quite human or Denizen.

===The Great Maze===
The Great Maze is a demesne that was ruled by Sir Thursday. It is a gigantic, chessboard-like arrangement of one thousand terraformed tiles, whereof each is one mile long and one mile wide. At each sunset the tiles change their locations, allowing any attackers to be split and easily attacked by the Glorious Army of the Architect; a means known as Tectonic Strategy. There are several fixed tiles, such as the Citadel, Fort Transformation, and a few others. The Citadel is the main Headquarters of the Maze, where Thursday himself makes his residence, and Fort Transformation is where new recruits spend a year of training before going on to serve the last 99 years of their tenure in one of the various factions in the Army.

Square 500/500, one of the four central tiles, is the “master square” of the Maze, in that no other square may move its location unless this one is unhindered. Therefore to fasten it in place (as in the novel Sir Thursday) is to render the Maze immobile.

At one end of the Maze is a mountain range. Within this range is a tunnel that connects to the Void of Nothing, by which controlled amounts of Nithlings are allowed into the Maze so that the Army may fight them. There are four gates within the tunnel; one gilded in gold, one in silver, one in bronze, and finally an Immaterial gate, the “Cleargate”. Each gate is operated by a single lever in the Border Fort above the tunnel. The gates are opened in various ways depending on the amount of Nithlings Sir Thursday wishes to be brought into the Maze.

===The Middle House===
The Middle House is a giant, thrice-terraced mountain consisting of three large plateaux previously under the control of Lady Friday. The plateaux are connected by the Extremely Grand Canal, a waterway whose water transports any writing to its desired destination. The workers of the Canal wear clothes made of out of paper covered with writing so that they float if they fall into the water. In Lady Friday, due to Friday's obsession with experiencing, it became thoroughly wintry.

Each of the plateaux, or “shelves”, serves a different function. The bottom, and the largest, called the Flat, is location of the Guild of Gilding and Illumination and of Letterer's Lark. The next shelf, the Middle of the Middle, houses the Guild of Illustration and Augmentation. Finally, the Top Shelf has the High Guild of Binding and Restoration. In between the Top Shelf and the crest is a crack in the mountain leading to the Eyrie of the Winged Servants of the Night.

===The Upper House===
The Upper House was ruled by Superior Saturday. It is in the Upper House where House Sorcerers are trained.

This demense is in perpetual rain, due to the fact that the Sixth Part of the Will was broken up into type and dispersed into the water. The Denizens working here have umbrellas to stop the water, but these are sometimes ineffective. Higher Denizens also collect water and let it drop in waterfalls on their inferiors. This enabled the Will to communicate with Arthur. The papers they work on stay dry despite the rain.

The ceiling of the Upper House is actually the floor of the Incomparable Gardens and is shrouded usually in clouds. Sunday constantly taunts Saturday by parting the clouds only for her, exciting her envy.

Saturday, for almost ten thousand years, has been building a tower with her private viewing chamber at the top while the other floors are slotted in below. The purpose of the tower is to reach and invade the Incomparable Gardens above and claim it for herself. Within the Upper House are four large Drasil trees located at the four corners of the Upper House that are constantly growing at a rate faster than Saturday can build her tower. As these trees grow, the Incomparable Gardens move further upwards. The tower is seventeen thousand feet high and the Denizens that work in the tower all have different coloured umbrellas which can be used to determine the floor upon which they are near. The basic building blocks of the tower are wrought iron cubes with a grille floor and no ceiling.

===The Incomparable Gardens===
Almost nothing is known about Lord Sunday’s demesne, the Incomparable Gardens. It is supposedly the most beautiful garden in the Universe, and is guarded by a variety of insectoid Nithlings resembling oversized worms and beetles. Dame Primus mentions that Denizens of this area of the House would be immediately noticeable in the Great Maze. The floor of the Incomparable Gardens is the roof of the Upper House and is constantly rising above the four Drasil trees which support it and grow to raise it. The branches of the trees attack anyone who comes near, and there are several beetle-like Nithlings guarding the trunks on the tree.

==Transportation & Communication within the House==

===The Front Door===
Controlled by the Captain and Lieutenant Keepers of the Door, the Front door is a huge three mile wide/tall dome. Every inch of the walls are filled with portals to parts of the house, for example the Upper House. Some protude into the Secondary Realms and the Void. In Lord Sunday, Leaf becomes Lieutenant Keeper, and senses the Void exploding through many of the entrances. She is there when the Great Maze collapses onto itself and the Realms are infected.
The entrance to the Front Door takes the form of a huge door a hundred metres high and fifty metres wide. From the start of Mister Monday, trouble occurs inside the Door. Superior Saturday, self proclaimed superior sorceror, sends her Dusk on many occasions, mostly through the Front Door. She sent him to kill Suzy and destroy the Border Dam in the Far Reaches.
Access to the Front Door is restricted, allowed only where the Door flows, like a huge ocean. Looking too much at the Door causes blindness and intense madness, such things may have happened to the Piper and some nithlings.
One of the side portals is Monday's Postern, which catapults the receiver straight into the Door. In Grim Tuesday, the Lieutenant Keeper sends Arthur to the Far Reaches to seize Grim Tuesday and gain sovereignty over the Far Reaches. He also sends Leaf to the Great Maze, as well as Suzy.

===Wings===
Wings are an everyday means of short-distance travel within the demesnes of the House. When used, they most often take on an angelic quality (i.e. white and feathered), but can have other appearances. Monday's Noon's wings are described as "white and lustrous" but stained with dried blood, Monday's Dusk's wings are black and "as glossy and dark as a raven's", and Pravuil uses wings that are yellow.

There are also different types of wings. Cheaper, paper-made wings are disposable, and are made for temporary use. They are unidirectional (up or down) and the user can only partially control them by leaning in the desired direction. Higher-quality wings can be taken on and off at will and are controlled by telepathy. Some of the higher-quality wings have special properties, such as the ability to shed light or generate invisibility in the Secondary Realms. Wings are banned in some areas of the House because of various air-borne hazards. In the Pit in the Far Reaches they attract Nothing from the clouds and this Nothing often forms flying Nithlings. Monday's Dayroom has a protective system against intrusion by fliers, in that superheated steam is shot at anyone who tries to fly over head. In the Upper House, Drasil branches invariably destroy any users of wings who fly above a certain height, however Saturday is able to circumvent this by using sorcery to repel the boughs. In the Great Maze, wings attract lightning (which is somehow related to the tile movements).

===Postage Service===
The House has an internal postage service, but this appears to be notoriously poor. Letters take weeks, or sometimes years, to reach their destination; most do not reach at all. This is due mainly to the disorder in the Lower House and has apparently grown worse prior to Mister Monday's downfall, having all the letters and newspapers cut off completely in some of the House, according to Piper's Child Fred Initial Numbers Gold. It is revealed in the fourth book that if a Denizen does not accept the military draft offered him, the Denizen will be turned into a brown-paper-wrapped parcel and transported through the postage system to the Great Maze.

===Elevators===
Elevators are currently the easiest way to travel between the demesnes of the House, save the Fifth Key, which lets the user go to any reflective surface in existence if its user has been there by another means. As the elevators fall under the authority of Superior Saturday, they are banned from the realms controlled by Arthur as of Lady Friday. The size of an elevator can vary greatly; it can be the size of a telephone booth or of a football field. When the elevator is in motion, its path is marked by a beam of light. In the Border Sea, elevators can only travel to Port Wednesday, as the rest of the realm is submerged. The elevators can be controlled by either the elevator's operator, Superior Saturday, or (probably) Lord Sunday.

===Weirdways===
Weirdways are pathways that exploit the veins of Nothing within the House. One is able to go through the Nothing via a dark corridor with soft and jellylike walls, floor and ceiling. Weirdway entries are often disguised as innocuous items within a room, such as a painting or coin on the floor or a clock , and they cannot be moved. According to Suzy Turquoise Blue, only the blood of one of the Morrow Days can close a weirdway.

===Transfer Plates===
Large discs that work as a sort of teleportation throughout existence. Transfer plates are usually electrum or (more rarely) fine china. Touching a transfer plate, intentionally or not, will automatically transfer a being to the prescribed destination of the transfer plate. The plates can be controlled by Superior Saturday.

===The Improbable Stair===
The Improbable Stair is a stairway that can traverse all of creation. It was the Architect's personal transport by which she visited all of her work. To enter the Stair, one must first have an item of power, such as a Key or the Piper’s Pipes. The traveler must then see a resemblance to a stair in any object, such as a bent blade of grass or jagged crack in a surface, and imagine the presence of a true stairway. There are several landings on the Stair, of which all open seemingly at random onto a place and time. Having reached a landing, the traveler must return to the Stair by the mentioned process. The entire use of the Stair is described as risky and dangerous, and these risks increase when the destination is near Nothing. Some Denizens cannot travel on the Stair (the reason for this is unknown); but Piper's Children are always accepted.

===Telephones===
Telephones are a means of communication within the House, and also to the Secondary Realms. The ring is inaudible to mortals, save Arthur and Leaf. House telephones resemble an early form of terrestrial telephone, and seem to work in the same fashion, in that they require an operator. During Lady Friday, Superior Saturday attempts to prevent Arthur from using them; but as they fall under the authority of the Lower House, and their wiring under the authority of the Far Reaches, she has limited success. The telephone operators are especially willing to connect Arthur, as he is the only one to give them the courtesy of saying "please".

===The Fifth Key===
Lady Friday's Mirror, the Fifth Key to the Kingdom, allows the user to summon a portal to any part of the House or the Secondary realms coming out through a reflective surface, most commonly a pool of water or a mirror on the wall. The places the mirror can access is limited to locations that Lady Friday has visited in person.

===The Lieutenant Keeper's Sword===
Albeit restricted to the Front Door, the Sword pulls the holder to wherever they need to go. For example, Leaf needed to check up on the Secondary Realms and was pulled as full force through the door.