Casterly Rock, nicknamed the Rock, is a fortress and the seat of House Lannister. The capital of the Westerlands, it overlooks the harbor of Lannisport and the Sunset Sea. Nearby strongholds include Kayce and Feastfires to the west, Sarsfield to the north, and Cornfield and Clegane's Keep to the south.
Legend says that Casterly Rock is named for the family that ruled it in the Age of Heroes, the Casterlys, who no longer exist. The Lannisters trace their rule over it back to Lann the Clever, who tricked the Casterlys out of their castle and claimed it for his own. Some claim that Lann still haunts the castle. After Harrenhal, the Rock is most likely the second-largest castle in the realm. It has never fallen.
The young Princess Rhaenyra Targaryen was once courted during a feast at Casterly Rock by the twins Jason Lannister and Tyland Lannister. During the Dance of the Dragons, Casterly Rock was left in disarray after the death of Lord Jason and the Battle by the Lakeshore.
Aeron Greyjoy was captured after the Battle of Fair Isle, taken to Lannisport in chains, and spent the rest of the Greyjoy Rebellion imprisoned in Casterly Rock.
When Tyrion Lannister became a man at sixteen, he was forbidden from taking a tour of the Free Cities as his uncles Gerion and Tygett had done. Instead Lord Tywin Lannister gave Tyrion charge of all the cisterns and drains at Casterly Rock.
After the death of Tywin Lannister in the Siege of King's Landing and the execution of Jaime and Cersei Lannister , the main branch of House Lannister was all but destroyed. King Renly I Baratheon exiled Tommen, Myrcella, and Tyrion Lannister across the Narrow Sea, and raised Lord Kevan Lannister up as the new Lord Paramount of the Westerlands, and Lord of Casterly Rock.