Dwarven Fortress

I had access to all the rooms of the underground fortress, except one: the large and heavy double metal door, located before the stairs that lead to the great main hall. I had been a guest of the dwarves for almost a week, I had been given permission to use the boat to visit the other parts of the kingdom, I had also entered the king's private room and the room of the magic glyph... but that room, no, I was not allowed. And every time I passed near it, a vibration of a strange energy permeated my body.
It was certainly the great secret of those dwarves