Princess Peach's Castle is the Capital Building in Toad Town. It is capital to the whole Mushroom Kingdom, and is the home of Princess Peach Toadstool, Toadsworth, and other Toads. It is unknown weather the Yoshi that sleeps on top of the castle is a resident or not.
In Super Mario 64, Bowser took over the castle and trapped Princess Peach, Toad, and all the power stars within the paintings that surround the castle, Mario had to then go through each painting, collect the Power stars, and save the Princess and Toad. Once doing so, the castle returns back to normal.
In Paper Mario, Bowser lifts the castle out of the ground, and into the sky. When the castle was lifted, Princess Peach was having a party, so the she and all of the party guests were taken up with them. Mario was thrown out of a window by Bowser, and had to go up there to save them once again.
Super Mario 64
Most of the rooms in Super Mario 64 were bare and only featured an enlarged portrait that acted as a gateway into a faraway land. There were plenty of different levels, though no distinct rooms.
Paper Mario series
The castle looks the same as it did in Super Mario 64. This time, there are more rooms inside the castle. For example: A kitchen, storage room, dining room, library, a balcony, and Princess Peach's room.
Mario & Luigi series
The castle played an important role in the Mario & Luigi series.
- Mario Kart: Double Dash‼ - Appeared on the Mario Circuit stage.
- Super Mario Galaxy - Princess Peach's castle could be seen in the beginning of the game when Bowser rooted it from the ground and took it into space. The final battle takes place around Peach's castle. When you finish the game with 120 stars with both Mario and Luigi, you can enter the Grand Finale Galaxy, and there you can see the castle more up close. Sadly, you aren't able to enter it.
- Mario Kart DS - Peach's castle appeared once more in Mario Circuit.
- Mario Kart Wii - Peach's castle could be seen next to the Mario Circuit track.
- New Super Mario Bros. Wii - Peach's Castle is one of the levels the player can access, though once inside the player can only watch videos by purchasing them with Star Coins. The beginning movie largely takes place within the castle as Mario, Luigi and a Blue and a Yellow Toad celebrate Peach's birthday.
- Super Mario 64 - Peach's Castle is where most of the levels take place in the game. It is full of paintings that Mario can jump inside.
- New Super Mario Bros. U - Peach's Castle is where the final battle takes place just like in Super Mario Galaxy.
- Wii Sports - Peach's castle can be seen in the background of Course 5 in Golf.
Super Smash Bros. series
The castle has appeared in both the original Super Smash Bros. and its sequel. In the original, it appears in the background of the stage of the same name, which actually takes place on platforms in the sky. In Melee, it would become the stage where players fight, featuring "!" Switches from Super Mario World and Banzai Bills who constantly attack the castle.
2D and 3D Differences
When playing a 3D Mario game, Princess Peach's castle has a lake under it. There is also a bridge for the entrance of the castle with a waterfall to the left. However, when playing a 2D game, Princess Peach's castle has no lake beneath it nor does it have a bridge entrance or waterfall.