The Walls
From The Maze Runner wiki
File:Maze-runner-concept-art.jpg
The walls in the maze
The Walls refer to the boundaries of the Maze surrounding the Glade, which rise hundreds of feet high. They change sections every single night, meaning that the Maze itself changes. It is built of gray stone and covered with thick ivy, they were immensely large barriers which forced the Runners to follow the paths laid out each time. Each day they form a letter of a code required to escape the Maze. A door at each entrance of the Glade also closes at night to protect the Gladers from the Grievers, but it is shown at the last of The Maze Runner that the wall didn't close for a night, then the Grievers attacked Glade, making the situation panic.
