Súthburg

In the earliest days of Gondor, its people had built a great fortress to defend Aglarond in the northern White Mountains. When, long afterwards, that land was ceded to the Rohirrim, they came into possession of that ancient stronghold, and gave it a name in their own language: Súthburg, apparently meaning 'southern fortress'.

In the days of Helm, Dunlendings overran Rohan, and the Rohirrim took refuge at the Súthburg and in the Deep behind. King Helm would sound his great horn before setting out against his enemies, and a legend grew up connecting the castle with Helm's horn. From that time the old name of Súthburg was forgotten, and the fortress acquired its more familiar name: the Hornburg.