a well cover

water wells have wooden covers a certain rocky mountain is dry but it has a vertical well cover as a door over a cave entrance around which a castle is built the cave is a dry vampire well in which they sleep till people travelling in bad weather need shelter and knock at the door and a pleasant old man with a welcome smile says "Well..." (gesturing his home as the local well...for peoples life fluids) "...come in...out of the rain... eat, dry, rest...stay the night" and they were brought into the flock stan sand