Ziggurat of Cornucopia

 was a spaceship powered by greed which hung over the planet of Cornucopia. For a long time it was known as a building. When the Ziggurat's original pilot died, it came to Cornucopia. It ejected a key called Star of Solitude, so a clever person could figure it out, then started a radiation storm to keep everyone in. The Star was picked up by Horatio Lynk, who didn't have enough greed to power the ship. The Eleventh Doctor destroyed the Star, exploding the Ziggurat, and freeing the people of Cornucopia. (COMIC: The Cornucopia Caper)