The acclaimed author of the Game of Thrones series, George RR Martin inspired by the Rock of Gibraltar

George RR Martin writes in his blog about how the Rock inspired him and the differences and similarities it bears with Casterly Rock. He tells of Gibraltar being a "unique place, with thousands of years of histroy". 

He describes astonishment about the rock, especially what you can find inside it, "it's not just a big hunk of stone, y'see...[there] are 34 miles of tunnels, more than 150 halls, chambers, and caves, Napoleonic gunports and cannons looking out over land and sea, stalgmites and stalactites, World War II bunkers, a concert hall/ampitheatre, a hospital (WWII era), and ancient mines."

This all came about after a visit to Gibraltar some years ago where he "found the place just as fascinating in personal as [he] had in print". 

You can read more about his thoughts and inisghts about Gibraltar and Casterly Rock on his blog: https://georgerrmartin.com/notablog/2022/12/23/a-couple-of-rocks/

The author also spoke to the Gibraltar Broadcasting Coporation for an exclusive interview about the inspiration. You can watch it here: https://www.gbc.gi/news/author-games-thrones-series-george-rr-martin-speaks-gbc-exclusive-interview