Black Archive

The Black Archive, also known as the Black Vault, (AUDIO: The Screaming Skull) was a secret vault maintained by UNIT in the Tower of London. The dangerous equipment it contained was such that even the Archive's own staff were forbidden to know what it held. (TV: The Day of the Doctor)

Aside from the main Black Archive vault in the Tower, there were several other related facilities, including Black Archive 5 in the South Downs (AUDIO: Armageddon) and the Vault under the Angel of the North. (AUDIO: The Screaming Skull)

Function
It functioned as a depository of everything that shouldn't exist on Earth but did anyway. At least one of the Black Archive facilities required a UNIT level one clearance to gain entrance. (TV: Enemy of the Bane) The staff at the main Black Archive had their memories erased after every shift. (TV: The Day of the Doctor) In the event of alien invasion the contents of the Black Archive were deemed so dangerous that the nuclear warhead situated 20 feet beneath the archive was to be detonated in order to prevent the invading species from gaining access to the technology contained within the archive. (TV: The Day of the Doctor)

was easily able to break in by tearing a small hole in space-time, although she noted that that the Archive was equipped with a mind field that would liquidate the brains of any intruders after 5 minutes. (AUDIO: The Lumiat)

History
During the reign of Elizabeth I, the Zygons, seeking to invade and colonise Earth, built a living support chamber beneath the Tower of London. After they had abandoned it, the organic walls calcified into black rock to one day become the Black Archive's vault. (PROSE: The Day of the Doctor)

The Doctor, during either his second or third incarnation, aided in the foundation of the Black Archive. (COMIC: Don't Step on the Grass) At some point, UNIT started keeping a particular eye on the Doctor's companions. They kept a wall of photographs of the companions in the Black Archive. Clara Oswald, and perhaps others, was taken to the archive as part of this screening. Her memories of the visit were subsequently erased. (TV: The Day of the Doctor)

On 4 June 1972, UNIT bought the Tunguska Scroll from a private collector and placed it in one of the Black Archive facilities. (TV: Enemy of the Bane)

Shortly after his dismissal from UNIT in 1995, Douglas Cavendish stole several items from the Black Archive and still had them in his possession by 2003, when Kate Lethbridge-Stewart helped him to defeat the Dæmon Mastho. (HOMEVID: Dæmos Rising)

Black Archive 5 in the South Downs was decommissioned in 2006. (AUDIO: Armageddon)

In 2009, Brigadier Lethbridge-Stewart smuggled Sarah Jane Smith into a Black Archive magazine to steal the Tunguska Scroll. (TV: Enemy of the Bane) During the same year, the Tenth Doctor sent Martha Jones there to fetch information on the Krynoid virus in the hopes that it might hold a key to stopping the Enochian invasion in Greenwich Park. (COMIC: Don't Step on the Grass)

In the 21st century, a vortex manipulator had been donated to the archive by Captain Jack Harkness. A Zygon impersonating Kate Stewart took Clara there to retrieve it. Clara used the manipulator to escape the Zygon, and travel to 1562 to rescue three incarnations of the Doctor. Having free reign of the base, the Zygons believed that they could overrun the Earth easily with the amount of alien technology now in their possession. The real Kate Stewart then turned up however, and activated the nuclear armed self-destruction mechanism located under the base. The Zygon who was imitating Kate was able to shut off the device, which was keyed to respond to Kate's voice, but the real Kate could likewise countermand it. This resulted in a deadlock between the two. Eventually the Eleventh, the Tenth, and War Doctors arrived to stop her. They activated the memory erasing equipment in the ceiling, meaning the two sets of people forgot whether they were human or Zygon, and stopped the self-destruction mechanism. This saved themselves and the whole of London, also resulting in peace talks between the humans and the Zygons. (TV: The Day of the Doctor)

The archive was later the repository of the Osgood Box, which symbolised the peace between humans and Zygons. By this point in its history, the Twelfth Doctor, along with Osgood and Clara Oswald, were allowed to access the archive. (TV: The Zygon Inversion)

Undated events
once visited the Black Archive while looking for information on, who she thought was an incarnation of the Doctor. (AUDIO: The Lumiat)

Inventory
Its inventory included the Tunguska Scroll, stolen by Sarah Jane Smith in 2009, (TV: Enemy of the Bane) Magna-Clamps, the head of a Cyberman, the head of a Supreme Dalek, River Song's red stillettos, a Time Agent vortex manipulator donated by Jack Harkness, a space-time telegraph originally given to Alistair Gordon Lethbridge-Stewart by the Doctor, allowing direct communication to the TARDIS, a board containing photographs of the Doctor's past companions, a Dalek Tommy gun, a chair from the Naismith Mansion, half part of Davros, TARDIS coral, a Clockwork Droid face mask, a pinwheel, a sonic probe, a Sontaran blaster, a damaged Dalek, (TV: The Day of the Doctor) a Mire battle helmet, (TV: The Zygon Inversion) and TOMTIT. (AUDIO: The Lumiat)

Once broke in through a hole in space-time to find information on  she presumed was the Doctor, she decided to "liberate" anything she found in the Archive's inventory that could be used as a weapon, or which she fancied as a souvenir. This included a Sontaran blaster, a Dalek Tommy Gun, the Cyber-head, the Mire battle helmet, the red stilettos, and finally TOMTIT, which she fondly called "old friend". (AUDIO: The Lumiat)

According to the Zygon that impersonated McGillop, the UNIT staff didn't know what half of the inventory did. The technology contained within the Black Archive could allow alien races that understood how it all worked to conquer the Earth in a day. (TV: The Day of the Doctor) During the negotiations of Operation Double, Clara Oswald observed the Tenth and Eleventh Doctors fiddling with the inventory, suspecting that they were disabling it. (PROSE: The Day of the Doctor)

Behind the scenes

 * In an interview after the broadcast of The Day of the Doctor, Steven Moffat revealed that the Black Archive was at one point also to house two movie posters for Dr. Who and the Daleks and Daleks' Invasion Earth 2150 A.D., which Clara was to have been seen examining, establishing the Peter Cushing films as existing within the Whoniverse. Unworkable rights fees prevented this from happening.
 * The Black Archive is also the title of a series of novella length critical monographs from Obverse Books.
 * The Black Archive is vaguely reminiscent of the fictional SCP-foundation. Both deal with the containment of dangerous things that shouldn't exist, both have a series of bases around the world, both use memory erasing technology to preserve secrecy, and both have on-site nuclear warheads in case the site is compromised.