Harrenhal

Harrenhal is a huge castle, the largest castle in all of Westeros, though it is also the most ill-omened. It is located in the Riverlands.

In the books
In the Song of Ice and Fire novels, Harrenhal is a colossal castle consisting of five massive towers (the Tower of Dread, Widow's Tower, Wailing Tower, Tower of Ghosts and Kingspyre Tower) and immense walls. The castle is located on the northern shore of the lake known as Gods Eye at the heart of the Riverlands, south of the River Trident and north-west of King's Landing.

The castle was built over 300 years ago by House Hoare, the ruling house of the Iron Islands which had overrun and conquered the Riverlands. It took three generations to construct. King Harren the Black completed the castle, boasting that it was impregnable. Unfortunately, the day he completed the castle was the same day that Aegon the Conqueror invaded Westeros. His dragons were not obstructed by the towering walls and roasted Harren alive in the tallest tower of the castle, now known as the Kingspyre.

Since Harren's death the castle has passed through a number of other noble houses (Qoherys, Towers, Harroway, Strong and Lothston), each of which has come to ruin. It is currently in the possession of House Whent, loyal vassals to Lord Hoster Tully of Riverrun.