City-ship

"Flying city."

- Jack O'Neill

A city-ship is a mobile city used by the Ancients. With roughly the same internal space as is found on Manhattan island, city-ships are one of the largest vessels in the known universe. They are also formidable battleships, although their effectiveness is severely reduced when in space.

Overview
"Look, the city, as you know, is just a giant spaceship..."

- Rodney McKay

The Ancients were already using city-ships several million years ago, when they departed Antarctica for the Pegasus galaxy aboard the city-ship Atlantis. At least one other Ancient built city-ship is known to exist in Pegasus; whether it was constructed there or was part of the Ancients' original migration is unknown.

A city-ship's design much more closely resembles that of a modern city than a spacecraft, with systems and living quarters distributed throughout several towers that extend away from the drive system; while in flight, the top of a city-ship would be considered the "front."

All known city-ships are capable of planetary landing; and indeed, they do not seem to have been designed primarily to function in space. Their hulls are not airtight, at least not in the majority of the ship, requiring the use of a shield to maintain atmosphere. As they are typically powered by three ZPMs, the shields are exceptionally powerful, withstanding days of constant enemy fire with just one ZPM; though probably as a result of this, the hull itself is quite fragile.

As evidenced by Atlantis, city-ships are inherently buoyant, capable of floating on the surface of a large body of water without any apparent technological aid; they can also rest on the bottom of an ocean, though again the shield is needed to prevent flooding.



Some city-ships, such as Atlantis, contain their own Stargates, located near the top of the central tower so that it may be easily accessed by puddle jumpers. On other city-ships, however, this location instead houses the control chair, which in Atlantis is located in another tower altogether.

City-ships carry a large number of drone weapons, which are apparently their only armament as city-ships were originally designed and built at a time when the Ancients had no enemies and could rely on ships for defense if necessary. (The Atlantis Expedition did, however, install railguns on Atlantis for use as point-defense weapons against the Wraith darts attacking the city, but these were unnecessary for the Ancients as weapons fire was no match for a shield powered by 3 ZPMs and the city's thousands of drone weapons could destroy any ships attacking the city.)

In addition, city-ships can host a myriad of other systems, many of which can be run without the need for a ZPM. Most of the offensive systems, such as the drones, can be run off a pair of Mark II Naquadah generators, in a state of barely controlled overload. They require a ZPM for extended operations however, as does the shield. The stardrive is designed to function with three ZPMs, but it is possible (though inadvisable) to fly the city with less. The Atlantis Expedition managed to do so with only one ZPM, albeit using additional energy supplied by an Ancient geothermal drilling platform.

Command and control systems
The central nexus of command within a city-ship was the control tower, which was the single tall spire in the center of the vessel. Inside the tower was the control room and (in Atlantis while it was occupied by the Atlantis Expedition) Stargate Operations where the crew operated the ship. This region contained such locations as the hologram room, conference room and the commander's office. The Stargate was also located here if the city-ship had one. Controls for dialing the Stargate, raising or lowering the gate shield and main city shield, activating the cloaking device (only on Atlantis, developed by McKay and Zelenka by interfacing a Puddle Jumpers cloak to the shield generators), and many other functions were located here. While this was the primary point of control for the ship, there was also an auxiliary control center located deep inside the city. The control chair was the main method of activating and operating the city's star drive, and could also be used to control and configure some of the city's systems; in theory, the control chair could also be used as a backup command center, although only one person can use the chair at any one time. If the control tower was destroyed, it was possible to relocate the command and control systems to another part of the city; however, the strain of governing the entire city was sometimes more than the local systems could handle.



An important part of the city ship was the chair room which contained a control chair that responded to the mental input of its user. Through this, a user with the ATA gene was capable of interfacing with the city's systems, allowing him or her to control the weapon systems of the ship. The chair was also used to control the navigation systems and hyperdrive, and could also be used to reconfigure power systems (and most likely numerous other systems as well).



Another command and control system presumably installed in all city-ships was the override mechanism. This was hidden in the Gate Room, concealed beneath the floor. New occupants of the city, unaware of the design specifications, might live in ignorance of the mechanism being present. Once a Lantean was present, the fail-safe could be remotely activated, after which it was designed to shut down the entire city and return it to Lantean control.

A city-ship possessed a highly automated computer system which was linked with the sensors and tasked with defending the city to a certain degree. When detecting a disease or pathogen in areas where the sensors were active, the city-ship engaged an automatic lockdown program which shut out users of the system. This was to prevent the spread of any illness by closing down systems such as the transporters and locking the doors in order to contain the spread of the disease. The city's sensors were sophisticated enough to detect any personnel wearing bio-suits (even those not designed by the Lanteans themselves) and allow those individuals safe passage to treat the infected.



These vessel's internal sensors allowed for the detection of individuals or objects inside the city. However, if power was shut down in a certain area then the sensors in that grid were offline and incapable of providing information to the control room. Another aspect of this sensor grid was the biometric sensor which was capable of detecting irregularities in biometric rhythm and reporting them to the system. This made it similar to a life signs detector; however, this more powerful city-based sensor was capable of discerning alien lifeforms from human, and reporting to the crew the presense of these aliens in the city. However, it required a significant amount of power to operate (though it was possible to focus the scanning field to certain parts of the city, thus reducing power requirements drastically).

In addition, the city-ships were equipped with powerful long range sensors capable of detecting distant ships, even if those ships were travelling in hyperspace. The data collected by these sensors could be routed through the control chair; the user of the chair could project a hologram using the information perceived by the sensors. This allowed for the remote viewing of locations on a planet's surface.

Hangar and transportation systems
Inside the city there were at least two hangar bays which contained a number of gateships slotted into various alcoves and platforms. External exits from these hangars allowed ships to leave the city and explore the surrounding areas. One of these bays was located at the peak of the control tower, and featured an internal door mechanism that allowed gateships to drop into the gate room and travel through the Stargate. Another bay was located underneath the city, and was rarely used by the Atlantis Expedition due to the fact it had become flooded by the time of their occupation of Atlantis; this bay was used by the team who retook Atlantis from the Asurans to enter the city without detection.

City-ships also possessed a number of transporter booths, which allowed a user to teleport to another booth inside the city; this transporter system allowed for the quick deployment and travel of personnel through various locations of the vast cities. The booths also served as elevators, allowing personnel to traverse different levels of the city without taking the stairs.

Hyperdrive and propulsion systems
The great city-ships of the Ancients, being for all intents and purposes little more than glorified spaceships despite their primary role as cities, possess their own fully-functioning sublight engine and intergalactic hyperdrive collectively known as the stardrive which they use to travel the stars. The stardrive required tremendous amounts of power, more than a single ZPM could churn out at once, and so at least two were typically required to successfully power the stardrive. In fact, only a power source on the magnitude of a ZPM could provide enough power to energize the inertial dampeners and provide enough thrust to allow the multi-million ton city to achieve escape velocity; the hyperdrive itself required relatively little power. If only one ZPM was powering the city-ship, other power sources were required to provide enough power to lift the city off of a planet's surface.

Offensive and defensive systems


A City-ship contained a powerful shield which was powered up by its ZPM hub, with even a single power module being capable of projecting a defensive barrier able to resist an orbital siege. This shield was literally impenetrable, but it was only capable of resisting an assault as long as enough power was available to keep the shield raised. It was possible to alter the shield generators in order to create an anti-Replicator field, meaning any Replicator or Asuran inside the city would fall apart whenever the shield is activated. It can also be converted to a Cloak. The shield was a vital component during space travel, as the vessel lacked a hull in a traditional sense and required the protective barrier produced by the shield generator to retain an atmosphere in the city - lack of a shield meant that the inhabitants of the city would be exposed to the vacuum of space, killing them.



The only known armaments these vessels possessed were a stockpile of drone weapons, as the city was built to be able to rely on its impenetrable shield for defense. These weapons were stored within the city itself, and they were launched from portals located at the edges of three of the city's piers. These weapons provided a high level of protection, and were quite capable of resisting fighter based assaults on the city and destroying any orbiting ships. Drone weapons were controlled through the city's chair room by someone using the control chair although individual drones can be fired using control consoles. A great deal of energy was required to charge the drones. This level of power was easily manageable when ZPMs were powering the city, but secondary power sources were only capable of providing enough energy to launch around a dozen drones.

Power generation systems
City-ships were created to utilize special power modules called Zero Point Modules (ZPMs) in groups of three to power the city to its full capacity. This energy distribution system was essential in powering the various aspects of the city, such as weapons, shields, and engines. Although it was possible to reinforce the power grid with other power sources, the system worked best with ZPMs. There existed a fine level of control over the distribution of power throughout the city, and it was possible to circumvent the flow of energy of certain sections of the city to other areas. One of the main power conduits ran beneath the control tower and led directly into the power module hub, much like an express lane. While it was possible to shut down other parts of the city, this conduit was required to keep the energy distribution grid moving along. The city also included a series of solar-powered generators which added to the power grid as well as energy from a mobile drilling platform if one was present and functioning.

Structure
From above, a city-ship resembles a giant snowflake-shaped platform dotted with skyscrapers. The majority of the taller buildings are located on the central area of the platform, while the smaller ones are situated along the edges of the six piers. The control tower (the largest of the buildings), is located in the exact center of the city, housing several important rooms including the gate room, the control chair (if there is no Stargate), the main jumper bay, and the holo room. The underside of the city contains the massive stardrive, an area to dock the city-ship around other buildings, and clamps to hold the city onto solid ground. Surprisingly, the hull of a city-ship is remarkably fragile in comparison to other space-faring vessels, and so a city-ship requires its powerful shield to protect it from such threats as orbital bombardment, natural weather phenomena, and the hazards of space travel.

Gate Room
This served as the central point in the City-ship as it served as a connection to the vast galaxy spanning Stargate network. Near the Stargate itself resided the hidden overide controls that can be activated by a Lantean giving them control of the City-ship. This chamber inside the city contained a doorway in the ceiling allowing for a Puddle Jumper to drop down and enter the Stargate. The Stargate itself was secured by a force field protecting it thus preventing enemies from entering the city. It was possible to disable the Stargate's DHD by removing the control crystal.

Not all city-ships contain a Stargate in their Gate room.

Operations Centre
Located directly opposite the Stargate was the main operations center which was used as a central command point for the city. This position allowed the occupants of the city-ship to monitor every aspect of the city's technologies and sensors as well as control its defensive shield (although drones were controlled from the Control chair in the chair room.

The destruction of the operations center can have a crippling affect on the management of the city-ship as some systems (such as internal sensors) would go offline as they can only be accessed via the OC for security reasons.

Auxiliary Control Room
City-ships contained an Auxiliary Control room similar to their Aurora class warships. It was capable of accessing the city's internal communication system and it was able to determine the status of the ZPM's power level. In addition, it was capable of activating enough systems within the City to deplete its power source.

This made it a vital location within the vessel and was capable of monitoring many of the systems on the vessel similar to the Operations Center. As such, it was capable of activating the City-ships Stardrive, although the Control chair is necessary to navigate.

Chair Room
The chair room was an important location in the ship and contained the control chair itself. From this chamber, a user was capable of controlling the city-ship's defensive systems such as shields or drones. It was also vital in the navigation of the city through hyperspace.

The chair was not always located in this room as there was one case where it was placed within Gate Operations if the Stargate was not there.


 * It's possible that the chair room was linked to the city's sensors in order to direct the drones as the Asurans were incapable of directing the drones into the water when the control center was destroyed, but once it was repaired, Dr. Beckett could.

Laboratories
The large nature of the city-ship allowed for a number of research laboratories to be present within the ship where scientific studies could be conducted. There existed numerous computer panels, displays and other forms of equipment with the rooms themselves varying depending on the form of research being conducted.

The Lanteans created a nanite lab on Atlantis where they created the Ancient nanovirus that evolved into the Asuran species. In addition to this, they also carried on research into Ascension with a special Ascension lab. They furthermore embarked on a mission of administering the development of Human civilizations through the society research lab. They also had a bio lab which contained facilities to study the life on a planet.


 * Only Atlantis itself has shown to possess research laboratories but presumably other city-ships contained similar such facilities.

Hologram Room
The hologram room was a specific chamber inside the city-ship which served as an archive where information was able to be conveyed to visitors of the room. A single computer display was present which could be used to activate the holographic display itself. This display took the form of a Lantean avatar that detailed various pieces of information depending on the program.

Most, if not all, programs were voice-interactive to a certain extent and could mimic certain behaviors, making it seem like a real person. The room took some power to activate which was why it was a burden to use compared to database terminals if the city-ship was low on power. The city-ship could also project holograms anywhere else inside itself.


 * Presumably, all city-ships contain similar facilities.

Conference Room
There are at least two known conference rooms present within the city-ship. A sliding doorway served as the entrance to the room. The first room was small and contained a rectangular table which was used for general meetings and discussions. The table itself was not fixed and could be removed.

The second, larger, room was used for bigger meetings and contained a ringed table which faced toward the multi-panel doorway. The Ancients used this room as the base from which their leadership governed their empire. The Asurans similarly used this room as the location wherein their Asuran Council sat during meetings with outsiders.

Living Quarters
City-ships contained a large number of chambers that served as living quarters for the crew of the vessel. The doorways into the rooms hold a door sensor that requires an individual to wave their hand across it in order to open the door. Inside, there were beds and other amenities. By the bed was another sensor that, when a hand was waved over it, activated or deactivated the lights for the room.

The door sensors seem capable of recognizing specific people (possibly with gene scanning technology), and when a door is locked, only the occupant or someone with a master system password can gain access.

ZPM Hub
The city was designed to be powered by a group of three Zero Point Modules, which could power the city-ship for thousands of years. This hub was a triangular structure with three ports, one at each corner, which accepted a ZPM. The ZPMs could be ejected or retracted into this ports without interrupting the power supply, as seen in the accompanying picture.

It was possible to alternate the power between the three modules allowing them to keep the city-ship powered for up to ten thousand years; however, this required the presence of a crew member to perform the switchovers over the centuries.

Gateship Bay
City-ships were equipped with a hangar bay which contained a large number of gateships and was also known (by the Atlantis Expedition) as the Puddle Jumper Bay. The gateships/jumpers were stored in alcoves and platforms arranged around the bay. The main bay allowed egress through both an internal doorway which led to the Gate Room, and an external door which opened onto the 'roof' of the control tower.

The city also contained a secondary Gateship Bay, which may or may not have been designed as an underwater access point (certainly, it was flooded during the time of the Atlantis Expedition). There were outer doors which could be remotely controlled, allowing for a jumper to enter the city, after which they were required to be closed in order to pressurize the bay. By the time the Atlantis Expedition occupied the city, these doors had jammed over the centuries, making opening or closing them difficult.

Underwater Gateship Bay Control Room
This was located on the other side of the underwater Gateship Bay and was a means of controlling the water flow as well as doors of the bay room. The control room was located in the next level with entry possible through a hatch that led into the chamber. There was a manual override that served as an emergency control mechanism in the center of the console. The manual override was required to be depressed constantly in order for it to activate the Gateship Bay room.

Drone Storage Chamber
Deep inside the vessel resided a chamber which contained a stockpile of drone weapons which were capable of being deployed at a moment's notice. The room contained numerous drones that were held in hexagonal containers where they waited for deployment into the launching chambers inside the vessel. It was possible for an individual to take a single drone and control it manually though this was dangerous.

There can be hundreds of drone storage racks present in the chamber but constant use can deplete a city-ships supply of drones which necessitates replacement weapons in the future.

Stasis Chambers
The city was equipped with an unknown number of stasis chambers where crewmen could be placed in a state of protective stasis. The chambers took the form of booths which appeared to be filled with some kind of 'icy' cube when activated. This state of stasis allowed personnel to survive for countless millennia in the city; however, stasis did not halt the rate of aging entirely, merely slowing it drastically (ten-thousand years in a chamber was shown to age a person as though sixty years had passed). Ultimately, an individual within the chamber will age to the point of death.

The stasis booths thus also served as a method of keeping terminally ill individuals alive, virtually indefinitely, until a cure could be discovered. There appeared to be a number of computer terminals on the sides of the chamber.

Transportation Booths
The city contained a number of transporter booths which allowed individuals to move from one such booth to another, thus allowing them to move from one part of the city-ship to another with ease. When a person entered into the booth, a display opened on the wall which contained a schematic of the city with dots representing other transporters. The occupant had only to tap one of the dots to be transported to the corresponding booth somewhere else in the city.

The Atlantis Expedition originally believed the booths were simple storage closets and accidentally discovered their true function.

Power and access to the transporters can be regulated by the computer system and power distribution grid.


 * Presumably, the booths were a variant of the ring transporter.

Holding room
The holding chamber was a large room containing a cubical prison cell where prisoners were detained. There are at least two holding rooms in a city-ship. The cell itself was of an unusual design, consisting of horizontal bars for walls and a powerful forcefield between them.

The forcefield had to be deactivated and the cell opened in order to allow entry into the cell if the crew wished to interrogate a prisoner. A control for the cell doors and shield are located in the external corner of the cell itself allowing for it to be shut down as long as the right sequence of commands and a valid access code were entered into it.

Grounding Station
City-ships were equipped with hundreds of lightning rods which were connected to four main grounding stations, which were used to channel lightning strikes away from the fragile hull of the city itself. The electricity was redirected into the water or ground surrounding the city, preventing any damage to the vessel. Two were located in the central part of the city while another two were located on its outskirts, near the edge of the piers. It was possible to disable a grounding station by entering a code which separated the grounding station from the rest of the city, causing a lightning strike to run rampantly within the corridors of the city-ship.

History
The most well known of all the city-ships was the capital of the Ancients known as Atlantis which departed Earth and left for the Pegasus galaxy between 15 and 30 million years ago. It served as the center of their government and was the last bastion of their civilization when the Wraith arose and fought them in the Ancient-Wraith War. The Lanteans were driven from their worlds until only Atlantis remained, and eventually they submerged the city and left for the Milky Way galaxy.

After discovering the location of Atlantis, the Tau'ri sent the Atlantis Expedition, which arrived at the city-ship and began to use it as a base of operations in the Pegasus galaxy. During their explorations, they discovered another city-ship which was partially underground. A third city-ship was discovered on the Asuran homeworld of Asuras. The Asurans attempted to use it as a means of destroying Atlantis but it in turn was destroyed when its ZPM core was set to overload.

Known city-ships

 * Asuran city-ship(s)
 * Atlantis
 * Asuran copy of Atlantis
 * The Tower