They were next to similar inscriptions which were more overlapping V's, apparently another inscription to ward off witches by referencing Mary using a Latin title.
However the inscription in the image is something different, despite looking similar. They mentioned that it was non-Christian.
It would have been sometime between 1300 and 1600. Does anyone have any more information on this sort of inscription?
Edit: To be clear, from what the guide said, the two V's in the image aren't alluding to the Virgin Mary, but are something else all together. They pointed to similar V's elsewhere and said those were, but that the ones imaged here are something else. Unless I've misunderstood.
I ran this past a non-reddit friend who is an expert on these marks and she sent the following information.
These marks are Ritual Protection Marks frequently placed on entrances into buildings as protection against evil (and witches). Your guide has correctly identified the conjoined Vs for Virgo Virginum - the Virgin Mary - virgin of virgins. There's also a circle which might be a daisy wheel symbol, which frequently has petals inside it. The marks have been taken for carpenters' marks, but they also appear on stonework and in caves where carpentry is non-existent.
This paper has more information about some marks found inside a cave and an appendix on ritual protection marks found inside houses which you might find interesting.
What part of the picture in particular are you referencing? The two triangles in the middle? The circle on the left side? The upside down house shape with horizontal lines in the right?