After House Manderly were granted the Wolf's Den 1000 years prior to the War of Conquest they began to construct annewer castle. As White Harbor started to grow so did the need for a new castle. The castle is situated at the top of a hill and it's great hall is called the Merman's Court.
At some point Ser Marlon Manderly was made captain of the garrison at the New Castle. His guards wear cloaks in the colours of House Manderly and wild tridents instead of swords.
A Dance with DragonsEdit
Ser Davos Seaworth visists the castle in the hope of gaining Manderly support for Stannis Baratheon. Wyman publically rejects him, however, and has Davos taken to the Manderly prison. He is later brought back to the New Castle by Robett Glover via a secret passageway. When he is there Wyman informs him of his plot to betray House Frey and House Bolton. He asks Davos to locate Rickon Stark.