Nulukkizdîn

"...before the proud ones came from over the Sea, Dwarves delved the halls of Nulukkizdîn."

― Mîm

Nulukkizdîn was a mansion of the Petty-dwarves, carved out of the rocks beside the river Narog in West Beleriand. When the Noldor returned to Beleriand, the Dwarves lost their ancient home, and Finrod Felagund founded Nargothrond in its place. Centuries later, when Nargothrond in its turn had been overthrown, the last of the Petty-dwarves returned here to reclaim Nulukkizdîn. This was Mîm, the betrayer of Túrin, and he was slain among the ruins by Túrin's father Húrin.

Curiously, it seems that the name Nulukkizdîn given in The Silmarillion may not be as Tolkien intended. The original manuscripts give variations on the name Nulukhizidûn, and in volume 11 of The History of Middle-earth Christopher Tolkien confirms that the published Nulukkizdîn is, strictly speaking, a misspelling. The correct spelling is Nulukkhizdîn.