Whitewalls

Whitewalls is a castle in the Riverlands, near the Gods Eye.

Prophecies of the Known World
Samwell Tarly mentions that Daemon II Blackfyre dreamt that a dragon hatched at Whitewalls, and preceived it as a sign that he would win the Iron throne. However, this was just a day before the Hand of the King put down Daemon's rebellion before it even started.