Wall

Aboard a prison ship, the Eleventh Doctor found walls that looked like doors. "Door-walls, if you like, or dwalls. Woors even, though you'd probably got it when you said they're not doors."

- The Eleventh Doctor.

He went on to say that it was "a big day if you're a fan of walls." (TV: The God Complex)

The Ninth Doctor once scrawled a sequence of numbers, 23 6 801, on a wall. (PROSE: Have You Seen This Man?)