The Drum
From Tardis Wiki, the free Doctor Who reference
The Drum was an underwater mining facility in Scotland in 2119.
Long ago, it was a city, but when a dam broke, the city was flooded and destroyed, leaving only a section which was converted into the Drum.
When the Twelfth Doctor and Clara Oswald arrived, they found the base overrun with ghosts, led by Prentis. (TV: Under the Lake)
