The valley was free over its entire width by the natural series of hills called Helm's Dike and behind that lay the fortress of Aglarond or the Hornburg, at the entrance to the Glittering Caves. A long causeway wound up to the great gate of the fortress itself. Inside the keep there were stables and an armoury, as well as a great hall in the rear which was dug out of the mountainside. There also was a great tower the top of which consisted of the great horn of Helm Hammerhand. The Deep, which stood next to the fortress, was barred by the long Deeping Wall, which consisted of solid rock except for a small culvert which allowed water from the Deeping Stream to enter; this rendered a fresh supply in sieges of great length, though this small weakness would eventually prove to be the wall's und