Chambers of Fire

A complex of tunnels and caverns bored into the eastern cone of Orodruin, known in Elvish as Sammath Naur, to which a road ran from Barad-dûr far to the east. Within the Chambers was a great fissure open to the fires of Mount Doom, called the Crack of Doom. Elsewhere in the chambers it seems that machinery ran ceaselessly (at least, a constant throbbing sound was heard). A tunnel led into the heart of a mighty volcano, needing to be constantly maintained and reconstructed by Saurons' Orcs. It was within this cavern, at the Crack of Doom, that Sauron forged the One Ring, and it was in the same place nearly five thousand years later that the Ring was finally destroyed, bringing about the Downfall of Barad-dûr.