Peach's Castle
Princess Peach's Castle is where Peach and many Toads, including Toadsworth, live. It was first featured in Super Mario 64, where the many paintings on the wall were used by Bowser to trap Toads, Power Stars and Peach. Mario had to travel through each to save the stars and progress through the castle's locked doors and ultimately save the Princess. In the original Super Mario 64, Yoshi sat on top of the castle and offered 99 extra lives and an improved jump ability once all 120 power stars were collected.
Super Mario 64 DS also featured the castle as its hub, but instead of first playing as Mario, Yoshi was the first character. Mario, Luigi and Wario all later became unlocked. Yoshi was not on top of the castle in this remake, as he was a playable character; however, there was a rabbit holding Luigi's last minigame and three 1-Up Mushrooms on the roof now. Due to these and other changes, this game is considered to be a seperate plot in the storyline in some (albeit very few) circles.
The princess's castle is also featured in Paper Mario, where Bowser uses the Star Rod to lift it into the sky. The princess, trapped in her own castle, goes on side adventures during the game. The castle is also the setting for the opening to Mario & Luigi: Superstar Saga. It returns to its original status as a hub for the game in Mario & Luigi: Partners in Time, where it is filled with time holes for the brothers to travel through and go to the past.
In the GameCube game Super Smash Bros. Melee, Princess Peach's Castle is used as one of the many battefields. In it, there are ! Blocks that turn on and off colored blocks throughout the area, and randomly Banzai Bills will come crashing into the side of the castle, exploding and KOing everyone in the blast radius.
Other games it appears in include Mario Kart 64, Mario Golf: Toadstool Tour, Mario Kart Super Circuit, Mario Kart: Double Dash!!, Mario Power Tennis, Mario Golf: Advance Tour, Mario Kart DS and others, be it as an object viewable on the track or the location of the playing field.