Helm’s Deep, also known as the Hornburg, is a mighty fortress set against the mountains of Rohan in Tolkien’s universe. It is a place of last refuge, built into the base of a mountain with imposing stone walls and a massive gate, fortified to withstand fierce assaults. The fortress features a long, curving deeping wall that defends the entrance to the valley, and behind it lies the vast Glittering Caves of Aglarond. The Hornburg tower rises proudly above, serving as the stronghold’s central keep, with a great horn ready to sound the call to arms.