- This article is about the space station. For the TV Series, please see: Babylon 5 (TV series).
- "...what is built endures. And what is loved endures. And Babylon 5... Babylon 5 endures."
- – Delenn
Babylon 5 was the fifth and final space station in the Babylon Project.
After the destruction of the first three Babylon stations and the disappearance of Babylon 4, The Earth Alliance cut funding to the Babylon Project. Due to these cuts, the construction of Babylon 5 was underfunded and was completed with the aid and sponsorship of the Minbari Federation. Babylon 5 came online on March 9th 2256 under the command of Jeffrey Sinclair.  A poll made by ISN at the time showed only 30% of people asked were in favour of it. By September 2259, it had risen to 40%. Lloyd's of London placed the odds of Babylon 5 surviving at 500 to 1; Las Vegas, 350 to 1; New Vegas, 200 to 1. By 2259, the odds had changed: Lloyd's of London, 250 to 1; Las Vegas, 200 to 1; New Vegas, 5 to 1. 
Babylon 5 was divided into six color-coded sectors: Blue, Red, Green, Brown, Grey and Yellow. Each sector was subdivided into 36 regions divided along 10-degree lines respective to the station core. Directions within the station were noted as spinward, retrograde, forward (toward the command sphere), and aft (toward the power plant).
Blue Sector comprised the forward section of the station and extends approximately 1.5Km aft to Red Sector and housed the maintenance and operational control centers, docking bays, customs, embarkation, the observation dome, the cobra bays and C&C as well as quarters for station personnel. Access to Blue Sector was mostly restricted to station personnel.
Red Sector was the station's commercial area. Businesses such as hotels, casinos, bars, the Zocalo and conference areas could be found here. Medlab, Security headquarters, and the Judiciary were also located in Red Sector. Access to Red Sector was unrestricted.
Green Sector, also known, as the diplomatic sector was restricted to diplomatic and command personnel. To accommodate the various diplomats and other guests, medlab facilities were also available in Green Sector.
Brown sector houses the industrial work that support the life support and waste reclamation facilities. It is located at the rear of the station's rotating section.
Grey Sector was the furthest section of the carousel aftward. Atmosphere monitoring, the alpha power station, fabrication furnaces and maintenance facilities could be found here in the sector's 30 levels.
Grey Sector's structure was incomplete due to budgetary restrictions. Due to the machinery, scans and communications were unreliable. The entirety of deck 17 was inaccessible via elevator.
Grey Sector access was restricted to Command, Security and maintenance personnel. Due to reports of missing persons and strange occurrences, Grey 17 was placed off-limits to all but Security personnel.
Approximately 3Km long, and aft of the carousel, Yellow Sector contained the primary fusion core, fuel tanks, and variable gravity research labs and zero-g maintenance.
The Central Corridors are a series of multi-level public access ways that run around the station's circumference and often serve as public areas and marketplaces. The Zocalo is situated in one such corridor.
Living quarters on Babylon 5 are divided up according to size, quality and function. Since space is at a premium on B5, larger quarters are charged more Earth. The quarters in Blue Sector are reserved for station personnel, including the command staff, support workers, station services, pilots, dock workers and visiting VIPs from Earth. The size of the quarters assigned to Earthforce personnel is determined according rank and position. In 2259, Earth Central decided that since the station had been running at a deficit that the quarters assigned to Captain Sheridan and Commander Ivanova were larger than was required, (by 7 feet) and ordered them to either move to smaller quarters or start paying 30 Credits a week each in rent. After a brief stand-off, Sheridan eventually resolved the issue by deducting 60 credits per week from the station budget set aside to maintain combat readiness and applying it against the rent, on the grounds that he's not ready to fight anybody until he's had a decent night's sleep in his own damn bed. 
Living quarters in Green Sector are generally reserved for Ambassadors, diplomatic personnel and visiting dignitaries and are paid for by their respective governments. Some non-diplomatic economy quarters in the are available to rent in the Alien Sector, for species that require alternate atmospheres.
In Red and Brown Sectors living quarters are available to rent for station visitors and vary from the small and spartan economy sized which contain little more than a bed, table and chair to the modest but well furnished business which comes with Babcom and data net access and entertainment terminals. The luxury class quarters are the finest and by extension the most expensive suites on Babylon 5 and come with a full range of amenities including a water (or racial equivalent) shower.
Downbelow is a term used for the various undeveloped areas of the station, mostly in the lower levels, near the outer hull, around the waste recycling system, the air compressors, and the water reclamation facility.
Downbelow is a hotbed of crime and accounts for as much as 90% of the station's crime rate, mostly because it's the only place for many people to go when they come to the station looking for a new life, but run out of money, unable to buy passage home, effectively becoming the station's homeless, referred to as Lurkers. The very worst parts of Downbelow are located in Brown Sector, which is a less than pleasant locale at the best of times. Downbelow is often divided up between an ever changing roster of various criminal factions, small-time thugs and gangsters. Most are little more than violent bullies that have learnt to survive by stealing, intimidation, protection rackets and extortion. Even the secretive Thieves Guild have a presence in this area. Downbelow came about as a result of budgetary cutbacks and a rush to finish when construction was nearing completion, leaving many areas of the station unfinished, especially in the Brown and Grey sectors. Quarters located in Downbelow aren't equipped with Babcom systems so residents must rely on public terminals.
In 2258 Dr. Stephen Franklin set up a free clinic in Downbelow to help treat those in need that couldn't afford to go to Medlab and to secretly sort runaway telepaths and get them out through the Underground Railroad.
Hazardous Materials Storage Facility
A small facility for the storage of hazardous materials orbited Epsilon III, at a safe distance from the station's orbit.
Core Shuttle & Monorail
Long distance, rapid transit on B5 is provided by use of the core shuttles and the monorails. The core shuttles run the length of the station's habitable areas, along the central axis and as such operated in a low/zero-gravity environment requiring passengers to make use of hand rails, mag-strips, seat-belts, and foot-straps. 
The transport tubes offer short to mid-distance transportation and are used mostly to move between levels.
- ↑ Infection
- ↑ And Now For a Word
- ↑ 3.0 3.1 Babylon 5 Security Manual
- ↑ 4.0 4.1 A Race Through Dark Places
- ↑ TKO
- ↑ Moments of Transition
- ↑ Interludes and Examinations
- ↑ JMS post on GENIE - 2/2/1995
- ↑ Grail (episode)
- ↑ Acts of Sacrifice
- ↑ JMS post on GENIE - 9/15/1993
- ↑ There All the Honor Lies
- ↑ Matters of Honor
- ↑ A Call to Arms
- ↑ Grey 17 is Missing
- ↑ JMS post on rec.arts.sf.tv.babylon5.moderated - 8/19/1994
- ↑ River of Souls
- ↑ A Race Through Dark Places
- ↑ Seen after the opening credits in The Illusion of Truth
- ↑ JMS Post
- ↑ The Gathering
- ↑ The Fall of Night