The sole purpose of the structure was to hide Puzzle from view during the day so that the Narnians could not see that he was not really Aslan. At night, when it was dim and harder to see, Puzzle would be let out and displayed for all to see, dressed in the skin of a dead lion. Since nobody had seen Aslan in several decades, the dim light was sufficient to deceive the unsuspecting Narnians. Shift used his "Aslan" to manipulate the inhabitants of Narnia, ordering them around on "Aslan's" orders.