Seventh Transept

The Seventh Transept was where the Headless Monks stored their leftovers: the heads of converts to their order. Most of them rotted to skulls, which which were very active and ate (or at least killed) rats and intruders.

The Doctor once went to the Seventh Transept to ask the head of Dorium Maldovar why the Silence wanted him dead. The Doctor later returned to the Transept in order to replace Dorium's head. (DW: The Wedding of River Song)