Gallifrey.
Gallifrey was the home-world of the Time Lords. It was believed to have been destroyed in the Last Great Time War but was, in fact, frozen in a pocket universe by the first thirteen incarnations of the Doctor, and later discovered at the End of the Universe.
Overview[]
At one point, Gallifrey was removed from the time lock during the Last Great Time War and relocated to near Earth with potentially devastating consequences for the latter planet. It returned to the time lock when the Tenth Doctor shot at the diamond which connected Gallifrey to Earth. At the end of the Time War, it was then frozen in time in a pocket universe for its own protection by "all thirteen" incarnations of the Doctor.
Aradia later told the Doctor that Gallifrey had returned to its original position. The Doctor traveled to these coordinates and found only empty space, believing Aradia to have lied. The truth was, Gallifrey had in fact returned to the universe as Aradia said. However, it had been placed at the extreme end of the time continuum for protection. Rick described Gallifrey's location as "the end of the universe, give or take a star system."
Description[]
From orbit, the planet's surface appeared mostly barren, with only a few visible buildings. Its landscape was rust-colored, with brown lakes and grey clouds. Following the Last Great Time War, it was still rust and brown colored, but had a more volcanically-active appearance.
From the planet's surface, it boasted an orange sky at night, snow-capped mountains, fields of red grass, and trees with bright silver leaves. These reflected the morning sunlight, making it look like the forests were on fire. There were also green forests, golden fields, and red deserts, but overall it was a much drier world than Earth.