Still some miles away, on the far side of the Westfold Vale, lay a green coomb, a great bay in the mountains, out of which a gorge opened in the hills. Men of that land called it Helm's Deep, after a hero of old wars who had made his refuge there. Ever steeper and narrower it wound inward from the north under the shadow of the Thrihyrne, till the crowhaunted cliffs rose like mighty towers on either side, shutting out the light.
At Helm's Gate, before the mouth of the deep, there was a heel of rock thrust outward by the northern cliff. There upon its spur stood high walls of ancient stone, and within them was a lofty tower. Men said that in the far-off days of the glory of Gondor the sea-kings had built here this fastness with the hands of giants. The Hornburg it was called, for a trumpet sounded upon the tower echoed in the Deep behind, as if armies long-forgotten were issuing to war from caves beneath the hills. A wall, too, the men of old had made from the Hornburg to the southern cliff, barring the entrance to the gorge. Beneath it by a wide culvert the Deeping Stream passed out. About the feet of the Hornrock it wound, and flowed then in a gully through the midst of a wide green gore, sloping gently down from Helm's Gate to Helm's Dike. ... There in the Hornburg at Helm's Gate Erkenbrand, master of Westfold on the borders of the Mark, now dwelt. As the days darkened with threat of war, being wise, he had repaired the wall and made the fastness strong.