The castle of King Lune in Archenland is Anvard.
Anvard is the fortified royal stronghold at the heart of Archenland, the mountainous kingdom south of Narnia. It is described as a moatless castle built of red-brown stone, set before a wooded ridge. In The Horse and His Boy, it serves as the central target of Prince Rabadash’s invasion plans.
King Lune’s court gathers there, and the castle becomes the setting where Shasta’s true identity is revealed. Shasta is recognized as Cor, Lune’s long-lost elder son and the twin brother of Prince Corin. The discovery restores the rightful heir to Archenland after he had been raised unknowingly in Calormen.
Anvard is easy to confuse with Cair Paravel, which is the castle of Narnia’s kings and queens, or Tashbaan, the capital of Calormen. After Cor and Aravis marry, Anvard remains their royal home, and their son Ram the Great becomes one of Archenland’s most famous kings.