Largest castle ever raised in Westeros, built by Harren the Black, King of the Isles and the Rivers, on the north shore of the Gods Eye. Forty years the ironborn king labored upon it, and on the very day the last stone was set, Aegon Targaryen came ashore at the mouth of the Blackwater.
The Burning
Harren boasted that no foe could breach his walls, and no foe did. Aegon's dragons flew over them. Balerion's fire melted stone like candle wax, and Harren and all his line perished in the Kingspyre Tower. The five great towers stand yet, blackened and half-melted, their broken tops like the fingers of a burned hand.
The Curse
Every house to hold Harrenhal since has withered and died, and smallfolk whisper that Harren's shade still walks the Wailing Tower. Its halls are too vast for any lord to fill, and House Whent keeps but a shadow of a garrison in a castle built for an army.