The Great Wall is one of the nine wonders of the world of ice and fire. The Great Wall of Despair spans the north of Westeros and is made of ice and snow. The Great Wall is the northern frontier of the seven countries, which separates the kingdom in the south from the wild land in the north and is regarded as the dividing line between civilization and barbarism by the people of the seven countries in the south.

During the construction process, the legend was endowed with the ancient spells and magic of the green prophet, the son of the forest, which could block the passage of aliens. It is speculated that Bran, the "city builder", laid a huge cornerstone anywhere possible along the mountain. Records in some documents show that the scale of the Great Wall at that time was much smaller than it is now. It is the night watchman's craftsmen who have dug up huge ice cubes from the frozen river in the ghost forest for generations and dragged them back to the Great Wall. After thousands of years of continuous reinforcement and construction, it has reached its present scale.

However, as people gradually forget the legend of the 8,000-year-old night, the significance of the Great Wall and the night watchman in people's minds has also changed from defending against the invasion of alien ghosts to defending against the savages from the north. The importance attached to the night watchman has also been greatly reduced, and its strength has shrunk seriously, limiting the daily maintenance of the Great Wall. At the beginning of the story of fire and ice, only three of the 19 fortresses built on the Great Wall were still stationed by the night watchman.