Bowser's Castle/Super Mario 64 Manifestation

Bowser's Castle's manifestation in Super Mario 64 is most commonly a replacement of Princess Peach's Castle, though it can manifest as a level, most commonly as the Eternal Fortress. This page will only go over the Princess Peach's Castle replacement version of Bowser's Castle.

Bowser's Castle manifesting in Super Mario 64 is usually the result of a Bad Ending causing Princess Peach's Castle to be replaced by Bowser's Castle, or as a secondary hub world alongside Princess Peach's Castle. It is described as a black and red castle owned by Bowser as a reskin of Princess Peach's Castle, with all of the Princess Peach stained glass replaced with the Bowser logo seen in Dire, Dire Docks.

Geography
Most instances of Bowser's Castle are a simple reskin of Princess Peach's Castle. This section will only go over the most common version of Bowser's Castle with a different layout from Princess Peach's Castle. Notably, all regular levels are kept, though can be reskinned. If there are new levels, they will usually replace a regular level or be found inside a regular level.

The Outside
The Outside part of Bowser's Castle, replacing the Castle Grounds, is described as a large ring of black rock around Bowser's Castle, but with a moat of lava in between the two, as well as a sea of lava surrounding The Outside. There is a bridge leading to Bowser's Castle in front of the entrance. There is a cannon to shoot to the roof locked until the player gets every star, as well as a hole somewhere in The Outside that leads to Vanish Cap Under the Moat. There is also a path leading outwards that ends in a portal to Lethal Lava Land. There is also another path but is locked by a key, which leads to Bowser in the Fire Sea when unlocked. Bowser in the Fire Sea unlocks the Top Floor.

Castle Roof
The Castle Roof is very similar to the Princess Peach's Castle version, with Yoshi and a Wing Cap box, but also a hole leading into the Top Floor.

Main Floor
The Main Floor is a floor replacing the First Floor, Castle Basement and the Second Floor. It is a large circular area with several paintings on the walls leading into most levels with paintings. There is a room that appears to be the Internal Garden, being a greenhouse with a grass floor, flowers and several birds and butterflies. Notably, the Big Boo's Haunt entrance is here, but set up in a way that it resembles a bird cage. Looking up in this area leads to Tower of the Wing Cap. Hazy Maze Cave is found by jumping into a large hole in this room, as well. Shifting Sand Land is accessed by jumping into a wall. Bowser in the Dark World is accessed by jumping into a Bowser painting, and unlocks the gate to Bowser in the Fire Sea. The Princess' Secret Slide, renamed to Bowser's Secret Slide, is found in the same room, but the stained glass is replaced with the Bowser logo. The Secret Aquarium is found by breaking a cracked wall below the Jolly Roger Bay painting by punching it and walking in.

Top Floor
The Top Floor is the replacement of the Third Floor, and is the final floor of Bowser's Castle. It is a small room with red carpet and several endless stairs that are unlocked by a varying amount of stars that lead to the Third Floor levels, including Bowser in the Sky.