Dare we call it a “Stone Shed”?
Does the idea of hanging moss, dripping water and a dark, quiet enclosure come to mind? Call it a cave, cavern or hollow and you’re getting close to both the ancient and modern-day descriptions of this sheltered stone destination in the cultivated or wild landscape.
If you’re following my ongoing Glossary of Garden Architecture, check out this just-added “definition” of a Grotto.