Hardhome, the nearest thing to a town that the wildlings created north of the Wall, was destroyed six centuries ago. According to the tales, Hardhome was burned to cinders, with the fire allegedly burning so hot as to be seen from the Wall. Later reports claimed that the devastation was “nightmarish”, and that screams could be heard coming from the caverns that pockmark the great cliff above the settlement. Some claimed that Hardhome had been set upon by slavers, while others claimed it was an attack by cannibals (V: 522).
There is no strong evidence, in any direction, concerning what actually happened at Hardhome, only speculation. However, the alleged timing of this event—600 years before the present—is interesting, as it predates the Doom of Valyria. Some have wondered if there isn’t a link between these events. One theory that has been put forward is that the devastation of Hardhome may be evidence of its having been a sort of “trial run” for the later Doom, suggesting an outside agency caused it. The culprits, in this speculative theory, would be the Faceless Men; in A Feast for Crows, it is implied that the Faceless Men were involved in the Doom (IV: 322). As the Doom involved a massive volcanic eruption that shattered the Valyrian peninsula, it seems likely that magic would in some fashion be involved in causing such destruction. This leaves open the possibility that Hardhome itself may be, in some fashion, volcanically active.
Another possibility connects to the screams allegedly heard from the cave mouths: could they be home to firewyrms? Described by the kindly man as being akin to dragons, but “boring” through soil and stone (IV: 321), the caverns, the fire, and the screams could perhaps suggest Hardhome is home to a nest of firewyrms. What roused them? Perhaps it was Faceless Men. Perhaps the Horn of Joramun, which is said to be able to awaken “giants from the earth” (II: 276), actually summon firewyrms? It’s a very speculative sort of speculation, with only supposition and guesses behind it, but it’s an intriguing possibility. Bear in mind that chapters such as Jon’s and Arya’s, discussing Hardhome and the Faceless Men and firewyrms, were once intended to appear all together in a single book, a fact that might have made intended connections by Martin more obvious.