Ark

The Ark was an enormous spacecraft built to carry the entire Human, Monoid, animal and plant population of Earth, which was falling into the Sun, to a new home on Refusis II. Since the journey would take 700 years, all but a few were miniaturized and placed in suspended animation.

The Doctor, Steven Taylor and Dodo Chaplet visited the Ark twice, once at the beginning and once at the end of its journey. It was Dodo who gave the ship the nickname of the Ark, as humanity had long since forgotten the story of Noah. (DW: The Ark)