Milestone

A milestone was a stone which marked the path to some destination, like a village, indicating proximity.

Often bearing an inscription, these markers were placed along roads, to guide travellers along their way. As evidence of history, standing still even as the landscape around them changed, the Third Doctor found some of these "fascinating".

On the island where the Master was being held prisoner, the Third Doctor pointed out an old milestone, which pointed out a way, in the fork in the road, to a settlement which had long fallen under the sea.

Clearing up the moss, which had collected over time, with a wire brush, produced from his pockets, he uncovered a name: Belial Village. Tired from walking, Jo did not share the Doctor's enthusiasm about this ancient marker. (PROSE: Doctor Who and the Sea-Devils)