- "The sky was extraordinarily dark - a blue that was almost black. When you had seen that sky you wondered that there should be any light at all."
- ― (Chapter 4) [src]
It was once a world accessible from the Wood Between the Worlds, but the pool dried up when the world ended. It is important both as the birth-world of Queen Jadis, the last ruler of the Empire of Charn (and later the White Witch of Narnia), and as the subject of a cautionary history concerning the eventual ends of unrestrained corruption.
Other known cities of the World of Charn, besides Charn, include Felinda, Sorlis, and Bramandin (all of which were mentioned by Jadis, and likely conquered by Charn).
The sun of Charn was old, red and far larger than the Earth's sun, and the sky was so dark blue that it was nearly black. When asked, Jadis said it had "always been so. At least, for hundreds of thousands of years." Also in the sky was a single bright, celestial object that hung left to the sun. It may have been a distant moon, another planet, or another nearby star.
The air of the world was thin and cold, and there was no water visible since the river of the city of Charn had all dried up, which meant no plants or animals remained alive. Before Jadis destroyed all the world's life, however, it had had a different appearance: according to her own description, it had, within her own lifetime as Queen, teemed with life and activity.
Charn once supported a vast civilisation of humanoids of an unknown species that had an average height of seven feet tall, and believed to have giantish heritage, though they were much smaller than true giants. It is possible the people of this world were a hybrid species of giants and Jinns, the latter giving some of them, such as Jadis, a magical ability which was, however, only found in those of royal blood, though it was mentioned that magic was somewhat common in Charn. The royals, however, were obviously the most powerful of them all.
The Hall of Images of past rulers in the royal palace indicated that Charn originally began with a golden age of wisdom and benevolence, but eventually turned away into corruption, cruelty and evil. Apparently, Jadis was the nadir of this degeneration, as her appearance is the most intimidating of all. Aslan calls Charn "accursed" and a "strong and cruel empire".
The ruined capital city of Charn, which the children landed in, stretched to the horizon, "as far as the eye could see".
The explanation for this is that all life on the planet was destroyed in a single petulant act of evil magic, the utterance of the Deplorable Word, by Jadis. It is unknown how long ago this occurred before Digory and Polly's visit, but long enough for stone palaces to fall down and stone statues to erode away. Perhaps this was long enough for the great river of Charn to dry up, or perhaps this was an ecological consequence of the destruction of life.
By the time of their visit, the planet was a dead and sterile world, in which the only living thing was Jadis herself. She had placed herself in magical suspended animation in the palace, awaiting possible rescue by chance visitors from other worlds. Jadis placed herself at a long table among the figures of other seated royals in a chamber called the Hall of Images.
During their accidental visit, Digory succumbed to curiosity or magic, and rang a magical bell that woke Jadis. She was then able to leave Charn with him and Polly.
Some time after the children and Jadis had left (we don't know how long because of the time difference between worlds), Charn the world was destroyed, "...as if it had never been", the natural end for a lifeless world with a dying sun and a fitting consequence of the evil that the Charn civilization had done.
In the Wood Between the Worlds, Aslan showed Digory and Polly a cratered grass thicket that once held the pool where the magical portal to Charn had been. He told them of Charn's fate, and warned that a similar fate could befall Earth if "tyrants who care no more for joy and justice and mercy than the Empress Jadis" acquired power similar to that of the Deplorable Word. "Let the race of Adam and Eve take warning."
The description of the rulers of Charn being initially wise and benevolent, but later becoming corrupted, cruel and evil creates a parallel with Númenor from J. R. R. Tolkien's works, where the inhabitants of Númenor were initially wise and benevolent, but later became corrupted and evil, resulting in the destruction of their realm by the Valar, as punishment for the Númenoreans' evil deeds.