Cair Paravel is the real anchor of that whole universe for me, in a way the woods or the lamppost aren't. It's not just a castle—it's the idea of a center. Narnia starts feeling like a kingdom the moment Peter, Susan, Edmund, and Lucy sail up to that coast and see the ruins. The rebuilding is the point. Every time I read 'Prince Caspian' and they're back to overgrown foundations, it hits different than if they'd just found some random battlefield. It's the heart that's been abandoned, and the story is about finding the pulse again.
I think Lewis was clever with the geography, too. It's on an island at the mouth of the Great River, right where the sea meets the land. That makes it a capital in the truest sense: a hub. The Telmarine regime ruling from a inland castle always felt off, like a suppression of Narnia's true nature. The sea, the talking beasts, the magic—it all flows to and from Cair Paravel. When the Pevensies rule from there, Narnia is 'right.' When it's empty or held by usurpers, things are wrong. It's a barometer.
The throne room with the four thrones is such a simple, powerful image. It visually enforces that idea of joint, legitimate rule. It's not one monarch's seat; it's a shared responsibility. Later books, like 'The Voyage of the Dawn Treader,' use it as the launching point and the home to return to. It gives the adventures a tangible home base, which makes the world feel lived-in and worth saving, not just a series of magical set pieces. The significance is that it turns Narnia from a landscape into a homeland.