I was thinking of the Castle of Chillon because of my earlier post, and looked up some more info. No wonder the place felt haunted! I still remember some 20 or more years later, how strange it felt. I knew about the first part, but not about the witches... (The following is edited...)
Byron's companions in that weird, wonderful summer of 1816 were his incredibly handsome but slightly loony bisexual physician, Dr. John Polidori; his dark gypsy of a mistress, Claire Claremont; Claire's fey, fanciful stepsister, the brilliant Mary Godwin; and Mary's lover, the poet, Percy Shelley. ...They were aware of the grisly past of those ancient walls and battlements, had heard tales of the countless souls who'd been confined, tortured and executed there -- including hundreds of women condemned as witches and burned to death in the castle courtyard.