Old Oak is a castle in the Reach. It is the seat of House Oakheart, a vassal house holding fealty to House Tyrell of Highgarden. The castle is located in the north-west of the Reach. It is north west of Highgarden on the Searoad near the border with the Westerlands.
In the books
In the A Song of Ice and Fire novels, Old Oak is the home of Ser Arys Oakheart, a noted member of the Kingsguard who accompanies Myrcella Baratheon to Dorne. He recalls that his home contains tapestries showing the Oakhearts fighting the Dornish in ancient times.
Old Oak · Red Lake · Goldengrove · Bitterbridge · Tumbleton · Grassy Vale · Cider Hall · Ashford · Horn Hill · Brightwater Keep · Bandallon · Honeyholt · Oldtown (Citadel · Hightower · Starry Sept) · Uplands · Blackcrown · Three Towers · Sunflower Hall · Arbor