The Fortress of Doors is the second location visited by Alice Liddell during the events of American McGee's Alice, after the Village of the Doomed. It is effectively a school (oftentimes written as "skool") which is bordered on all sides by a large stone wall. It is the home of the Insane Children and also inhabited by several Card Guards and Boojums. From the Fortress of Doors, Alice retrieves the ingredients required to create a miniaturizing potion so that she could follow the White Rabbit into the Vale of Tears, as well as the Croquet Mallet and Demon Dice. Alice finds her first Rage Box in this section of the game.
The Fortress of Doors is generally quite a large area that proceeds the Village of the Doomed. It is full of Doors and moving platforms that can confuse and anger the player at certain points. There are mainly Card Guards scattered throughout this area. The floor is tiled in back and white and most structures are built of stone. The world is standing on nothingness and appears to be floating through a massive portal that swishes around colors of blues and purples blended together.