Cirith Gorgor

(S. "Haunted Pass") a high pass where the mountain ranges of the Ered Lithui and Ephel Dûath meet in the far north-western corner of Mordor, the pass opens out into the mountain vale of Udûn, and was guarded from the beginning of the Third Age by the Towers of the Teeth. When Sauron returned to Mordor c. TA 2951 the Morannon was built across the Pass.