You can hear the song from miles away. The song is enchanting in a mild way. Even the plants sing this haunting tune all day. This gives you fair warning to be ready to dance to a different tune. You are leaving your country and entering theirs.
This relic, while of little value against the living, is a formidable tool against the beasts from beyond.
The D’athri took to space in such a way to make Terrans look "gun shy". They can be found in small numbers in and around every space port in Known Space.
A little way up the narrow valley, before they reach the woods, the PCs notice the squat, tumbledown buildings by the riverside. They are hardly big enough for a human to stand in, and the complex cogs and shafts that occupy the central cavity of one of the buildings are perplexing. What were these buildings? And how safe are they to explore?
Alternatively a desolate place is the perfect setting for a derelict chapel or croft. There needn't be any actual physical encounter involved, but it adds atmosphere to a place to see its dead history. For instance, in the Outer Hebrides there are whole deserted villages which were razed to the ground by the English during the Clearances. Such stories give a setting authenticity and character.