The Library

The Library was a planet-sized library that was built during the 50th century. It contained every book ever written. Within its core was the largest hard drive ever designed to date, which served as an index computer, as well as containing backup copies of every book ever written. The planet had one moon, which was actually an antiviral subroutine having the physical appearance of a moon. Due to its caretaking role, it was known as a Doctor Moon.

Creation
The Library was commissioned by Felman Lux and was managed by a head Librarian. Visitors to the Library used courtesy nodes, sculpted computer terminals containing real faces made from donated flesh; the nodes would chose a face they thought a patron would like. The security drones were levitating wooden spheres. All spheres had a camera lens and could communicate by displaying messages across a scrolling LED display in red letters. Visitors were advised to switch off their mobile comm units for the courtesy of other patrons in the library.

Paper editions of every book ever written were made specially for the Library. (TV: Silence in the Library) The forests cut down to make the books were home to Vashta Nerada, which then hatched from the books and infested the Library. When the Vashta Nerada hit their hatching cycle and began their attack, someone in the Library set off an alarm that made the computer teleport everyone out of its halls and covert them into a virtual form for transmission to a safe location. However, the computer could not reconstitute anyone back to physical form, because it had no place to send them where they would be out of reach from the Vashta Nerada. Instead, the computer managed to "save" all 4022 visitors to its hard drive, where they could dream an imperfect virtual existence. (TV: Forest of the Dead)

Arrival of the Doctor and River Song
The computer sealed off the planet to quarantine the Vashta Nerada, and it would be 100 years before the Lux family could arrange an archaeological expedition led by Professor River Song to get back inside the Library.

The Tenth Doctor and Donna Noble arrived after being asked to come by River Song, via his psychic paper. (TV: Silence in the Library) River's expedition crew was gradually attacked and devoured by the Vashta Nerada, who began stalking the group for meat. Trying to escape, Donna accidentally teleported herself into the virtual reality set by the computer. Inside the Library, the Doctor learned that the computer's hard drive contained the consciousness of Charlotte Abigail Lux. To protect her identity and their child, the Lux family made the Library computers refer to her by the protracted name "C.A.L.". The grandson of her father, Strackman Lux, had been trying to find Charlotte and ensure she was still safe. (TV: Forest of the Dead)

The Doctor helped to return the visitors and reached an agreement with the Vashta Nerada to make sure no one arrived in the Library again. However, River had to give her life to provide the computer enough memory to return all 4,022 people and Donna to the real world, refusing to let the Doctor make the sacrifice. Soon after her physical body was lost, the Doctor found her data ghost stored on his future self's sonic screwdriver and uploaded it to the computer, where she would be able to live on with her expedition crew, whose ghosts had also been captured by the computer. (TV: Forest of the Dead)

After entering the Doctor's time stream, a copy of Clara Oswald ended up in the Library, watching the Tenth Doctor. (TV: The Name of the Doctor)

Later visit by the Doctor
The Eleventh Doctor and Amy Pond later visited the Library, where they encountered the Book Monsters. (COMIC: Booked Up)