DOCTOR: I'd say it should take me about... ohhh... three thousand years. Less, if I could find a way of stopping myself getting distracted.

SCARLETTE: Three thousand years. To become a creature of pure light.

DOCTOR: I'm trying to decide whether it'd be worth the bother.

On one occasion, Fitz even claimed it had its own opera house, although the Doctor quickly added that he'd only picked that up by accident, having intended to deliver it somewhere before forgetting all about it.