Those are kitchen fireplaces. They're big enough to roast a whole ox or pig.
In another castle I visited there's a haunted kitchen- where a ghostly woman has been observed placing a baby in a fireplace very much like these.
Hmmm: I seem to remember that some fireplaces actually had seating at their edges.
If one agrees with Jung's theory, that great emotional conflict leads to "markers" in terms of the archetypes, then maybe that's what happens with ghosts, too--when there's a moment of emotional upheaval, it's marked by energy-in-the-air, visible.