The Castle Wall is an upgrade from the Stone Wall, and is the strongest wall in the game. Its color scheme resembles that of the Stone Wall, but it is octagonal in shape.
- The Castle Wall is unlocked at age 7, and is only available if you chose the Stone Wall at age 3.
- Castle Walls cost 35 Stone points each.
- The limit on Castle Walls is 30.
- Castle Walls have 1500 health points.
- Players and Mobs cannot move through Castle Walls, nor can arrows or bullets.
- Arrows have no effect on Castle Walls.
- The stone icon on the bottom right of the game's GUI uses the Castle Wall's sprite.
- The Castle Wall is an alternative to the Turret, Platform, and Healing Pads.
- The Castle Wall is the biggest wall.
Castle Walls were first added in version 0.22. At the time, Castle Walls were available at age 5, cost 1 Stone and 1 Wood and had 1,000 HP. They were quickly removed in version 0.25. However, Sidney said he would put Castle Walls back in the game eventually, and he did in version 0.68, buffing their health to 1,500 in the process. At that point the wall limit was 25, but in version 0.891, the Wall limit was increased once again. Since then the Castle Wall has not changed, making it the least changed wall in the history of MooMoo.