Princess Peach's Castle/Unidentified Floors

Unidentified Floors are floors or areas of Princess Peach's Castle that have minimal reports, so it is hard to confirm them, though they have been reported by credible people so they may potentially exist. There have been several Unidentified Floors, and most of them have several distinct features. The Unidentified Floors are considered dubious due to their nature and that some of them appear to defy established limitations of the Personalization A.I.

Floor 3B
Floor 3B is the most well-known Unidentified Floor, and is a third basement. It is described as an area reusing several paintings from base copies, though has several parts that would appear to lead somewhere that have no paintings or doors, simply making them empty hallways and walls. It also reportedly can change appearances at certain segments, and a report has stated that a Mad Piano is on this floor, though it is not known if this is a consistent feature or copy-specific.

The Castle Outskirts
The Castle Outskirts is described as a large area similar to the Castle Grounds and anomalous Castle Fields, though there is a ravine split in the middle, and no castle is present. A pipe has been reported in this area, though it is not known where it would lead. This area has minimal information on it, and it is unknown if it entirely replaced the Castle Grounds or is simply a similar area.

The Mirrored Castle
The Mirrored Castle is a supposed clone of the castle that can usually be accessed by going behind the mirror in the Second Floor's mirror room. It can reportedly consist of just the Second Floor, or the entire castle, including anomalous floors. Notably, in this version, the inaccessible paintings on the Second Floor have been reported to actually lead to levels. These levels are usually established anomalous levels, though some unique levels have been reported as well.

The Horror Hallway
Not to be confused with Hollow Horror Halls, the Horror Hallway is an area that can reportedly be accessed in any part of the castle through unknown means. It is characterized by a sudden decrease in saturation, music changing to become "scarier", and any hallways becoming seemingly endless. The Horror Hallway area can be exited by entering another part of the castle, or a level. It is currently not known where the hallways lead, if they do actually lead anywhere.

The Castle Kitchen
The Castle Kitchen is a reported part of a floor with an oven, fridge, microwave, etc. A chef Toad has been reported, who would give the player a star after the player helps bake a cake, or simply upon talking to them similarly to other Toads throughout the game. This kitchen area can also reportedly lead to Delicious Cake, usually after baking the cake for the chef Toad.

The Mario Statue
The Mario Statue is the name given to an anomalous area similar to the Toad Shrine resembling a large statue of Mario in a large, otherwise empty room. No other objects or events have been reported in this room, appearing to indicate this was scrapped before it was finished or created by the Personalization A.I. based off of the Toad Shrine.

Bob's Documentation
The Youtuber Bob has documented Floor 3B, and the Castle Outskirts. Floor 3B has been shown in 2 videos as simple screenshots, though Floor 3B is explored in the video fittingly named Floor 3b. It is explored, and it displays the unnatural appearance of parts of the floor. Near the end, Bob enters a hole in the floor next to a Princess Peach painting, and a screenshot of the World of Dreams' Pathway area appears, alongside text saying "Go to the world of dreams." and "Find the key to the 4th".

In a previous video from Bob named Bomb Omb Village, where Bob explores Bob-omb Village, they suddenly appear in the Castle Outskirts towards the end of the video. They briefly explore, before finding a warp pipe and entering it as the video ends. It is not stated where this pipe leads to.