From A Wiki of Ice and Fire
Clegane's Keep is the semi-canonical name given to the seat of House Clegane, which is located southeast of Lannisport in the Westerlands. There is a village under the keep. The keep has a fearsome reputation, one that lives up to that of its lord, Ser Gregor Clegane. It is said that servants disappear unaccountably, and even the dogs are afraid to enter the hall.
The keep was given to the first Clegane knight, the kennelmaster at Casterly Rock, who saved Lord Tytos Lannister from a lion and lost a leg in the effort. A woodcarver set up shop in the village and made toys for the young Gregor and Sandor Clegane; a dispute over one of the toys led to Gregor burning the face of his younger brother. After a hunting accident killed the boys' father, Gregor inherited the keep and estates and Sandor left to serve House Lannister.
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