Trenzalore

Trenzalore was the name of a place that, according to Dorium Maldovar, would be where the First Question in the Universe (Doctor Who?) was answered truthfully, and that the Doctor would arrive there at some point in his travels. The religious order known as the Silence was determined to ensure that the Doctor never reached Trenzalore.

Dorium also mention that when the Doctor went there it would mean the fall of the Eleventh. This could mean that this is the location where the Doctor regenerates. (DW: The Wedding of River Song)