Bubble universe

This bubble universe was a tiny universe which was home to the sentient planetoid known as House. House lured Time Lords from the main universe through the bubble universe rift so it could consume their TARDISes. The Eleventh Doctor and many other Time Lords were drawn to the bubble universe by distress hypercubes, presumably those of House's previous victims. Notably, the Bubble Universe also included a junk yard filled with dead TARDIS parts left behind by Time Lords lured into House's trap. The bubble universe was destroyed soon after House left it inside of the Doctor's TARDIS. (TV: The Doctor's Wife)

Behind the scenes
In the script for TV: The Doctor's Wife, writer, Neil Gaiman, described the junk yard as "the Totter's Lane at the end of the universe." (CON: Bigger on the Inside)