Battle Fort

Battle Fort is a level that appears in Super Mario 64 DS. It is found by jumping into a hole in the Castle Courtyard that is covered by boxes.

Geography
Battle Fort is a large square area inside of a cage. The bottom is made of dirt, with several structures and boxes around the level. There is also a path at the top of one of the structures that leads to pole of the center of the level. This level's enemies are Chuckyas, Big Steelies, Goombas, and Heave-Hos.

This level's star is obtained from collecting 5 Silver Stars, which are dropped by Goombas, inside of boxes, and at the top of the pole in the center of the level. The star will appear in a corner of the level.

Super Mario 64 Manifestation
In some personalized copies of Super Mario 64, Battle Fort has been reported to appear. It will usually appear the same as it does in Super Mario 64 DS, though with a red coin star instead of a Silver Star star unless that copy has Silver Stars. Notably, some personalized copies reportedly have a painting similar to the unused Battle Fort painting. Some personalized copies indicate remnants of a multiplayer mode within the stage. A timer with a star counter is added, much like the VS mode added in the DS remake. However, it is impossible for a second player to join in, leaving the player to compete against no one until the timer runs out.

Unused Painting
Found in the files of Super Mario 64 is an unused painting that appears similar to Battle Fort when looking at it from a top-down view. It is currently unknown why this painting was scrapped. However, some say it can appear in place of the typical entrance somewhere in the Castle Courtyard or an extra room in Princess Peach's Castle. This is likely due to the Personalization A.I. trying to make use of this unused asset.

Level Expansion
Some say that the level can be expanded into a full course, which commonly correlates with the unused painting spawning. How exactly is inconsistent, with most saying that the walls around the level are pushed back, revealing more similar geometry with other missions, such as finding 8 red coins, finding a star hidden in a box, having to climb up a pole and then jump across floating platforms to a star, or even fighting Big Bob-omb. Why they appear in this area is unknown.