His Domain

Not to be confused with Bowser's Domain, another anomalous hub area with a similar name.

His Domain is an Alternate Castle found on some personalized copies of Super Mario 64, typically replacing Princess Peach's Castle as the main hub world of the game. It is typically described as a large castle-like building owned by Bowser, similarly to Bowser's Domain, but more coherent. It reportedly also contains several other anomalous levels, such as Flying Fortress, Hollow Horror Halls and Cold, Cold Crevasse, most of which typically appear to be anomalous versions of levels seen in the base game or at least very similar in design. His Domain reportedly most commonly appears after the player encounters a Bad Ending in the main game.

Description
His Domain is generally described as a large fortress-like structure with several doors leading to various locations, typically ending in a path to a level of some kind. It resembles the castle in design, though it's overall map and contents are rather different. The rooms typically use a gray texture of some kind with a lot of the walls being made out of brick. There are also some outside areas, reportedly showcasing a sunset-like skybox. His Domain also reportedly has rooms resembling other anomalous locations seen throughout Princess Peach's Castle, such as the Internal Garden, Peach's Bedroom, the Castle Balcony and even the dark room seen in the Castle Garden. Other notable locations include a poorly lit room with a large hole in the floor that typically leads to Hollow Horror Halls, and a large library-like area that reportedly has unique readable book objects and even an old Koopa that the player can talk to.

Notably, several signs scattered throughout His Domain reference a group called the Koopa Krew, which are apparently a group of Koopas that have built His Domain and several other Bowser-related locations, such as his castle that several reports claim is alluded to. Some reports claim the player can even find this supposed Koopa Krew somewhere in His Domain or some other area in the game, usually just having random dialogue though some claim they can unlock something, such as giving the player a Power Star similar to some Toads in the base game.

Associated Levels
His Domain has been associated with several anomalous levels, though these are the ones we either have the most information about or are most commonly reported alongside the area.

Flying Fortress
Main Article: Flying Fortress

Flying Fortress is an anomalous version of Whomp's Fortress with a similar overall design. It reportedly has several unique missions, as well as a sub-area that is apparently the equivalent of Whomp's Fortress Interior called the Fortress Internals that is a black void with several towers sticking up that allows the player to navigate the location.

Cold, Cold Crevasse
Main Article: Cold, Cold Crevasse

Cold, Cold Crevasse is an anomalous level reportedly found in Cool, Cool Mountain but several reports say it can appear on it's own in His Domain. The level is typically a large ravine-like location with several platforms used to navigate around, though other reports associated with His Domain says it is much similar to the regular snow levels with several houses and other unique areas.

Hollow Horror Halls
Main Article: Hollow Horror Halls

Hollow Horror Halls is a large maze-like area with a blue tint similar to Big Boo's Haunt in theme and design filled with Boos that requires the Vanish Cap to navigate some parts. Unlike the other levels in His Domain, this is typically not a full course. This is one of the levels in His Domain typically associated with a specific room, usually being a large dark room with some opening such as a painting or hole in the ground.

Daffodil Meadow
Main Article: Daffodil Meadow

Daffodil Meadow is an anomalous version of Bob-omb Battlefield that typically appears in one of the many outside areas of His Domain, with lighter grass and the river that was allegedly in an early design of BOB, as well as a cave sub-area. It also reportedly has a unique boss fight against a character similar to Child of Big Bob-omb, though the boss is usually still just Big Bob-omb.

Bowser in the Broken Realm
Not to be confused with Bowser in the Randomized Realm, a similar level found in Floor 2B.

Main Article: Bowser in the Broken Realm

Bowser in the Broken Realm is the Bowser level most commonly reported in His Domain, being a large area with floating pieces of Princess Peach's Castle scattered around with numerous different enemies that the player has to deal with. It also reportedly has a unique intermediate area leading up to the Bowser boss fight, and is supposedly connected to the Eternal Fort in some way.

Empty Grounds
Some reports of His Domain claim that the Castle Grounds is empty, with a pipe leading to His Domain in place of the castle. This appears to fit the idea that this area is connected to a bad ending of sorts, as it implies that Bowser destroyed the original castle and built His Domain in it's place. There is also occasionally a sign in front of the pipe, which most commonly says nothing, implying it was unfinished or the A.I. failed to generate any text for the object.