Hammerhorn, also called the Hammerhorn,[2] is the seat of the main line of House Goodbrother in the Iron Islands. The castle lies in the Hardstone Hills[2] in the southwest of Great Wyk.[1] Its maester is Murenmure.[2]
Layout
A large square castle, Hammerhorn has spiky iron battlements and iron gates. The stones used for its construction were quarried from the cliff behind it. Below its main entrance lie the openings to the mines and caves within which toil the smallfolk in service to House Goodbrother.[2]
The shadowy hall of Hammerhorn is dank, drafty, and smoky.[2]
Recent Events
A Feast for Crows
After learning of the death of his eldest brother Balon, King of the Isles and the North, Aeron Greyjoy travels with Gormond Goodbrother to Hammerhorn to meet with the youth's father, Lord Gorold. Aeron wants to speak with Gorold alone in the hall, but the Lord of Hammerhorn insists that Maester Murenmure remain. Aeron is shocked to learn that his hated elder brother, Euron Crow's Eye, has claimed the Seastone Chair. Gorold offers to host Aeron overnight at Hammerhorn, but the Damphair departs Hammerhorn for Pebbleton in the company of Greydon Goodbrother.[2]
Chapters that take place at Hammerhorn
Quotes

Gorold's keep was hulking and blocky, its great stones quarried from the cliff that loomed behind it. Below its walls, the entrances of caves and ancient mines yawned like toothless black mouths.[2]
—thoughts of Aeron Greyjoy