Oldcastle is the seat of House Locke in the north. It lies on the northern shore of the Bite, southeast of White Harbor and north of the Three Sisters.
Oldcastle was the royal seat of House Locke when they were petty kings.
Maester Aemon sends a raven to Oldcastle in a plea for help to defend Castle Black from wildlings.
According to Wyman Manderly, Lord of White Harbor, the Lockes of Oldcastle will take their lead from him.