Mario's castle

Mario's castle (or Mario Castle) is a castle that appears in Super Mario Land 2: 6 Golden Coins. Wario steals the castle and transforms it into a level. According to Nintendo Power, he renamed it "Wario Castle."

Inside are metal spiked balls, Piranha Plant-like footholds that spit fireballs, and traps shaped like Wario’s gloves that try to crush Mario. Extremely odd creatures live here, such as Floating Faces, a type of bouncing ball with Wario's face on it. If Mario beats Wario, the spell is broken, the castle turns white instead of black, and its M, turned upside down to resemble a W, is moved back into its correct position.

In later games, the Mario Bros.' House replaced the castle as Mario's place of residence in the Mushroom Kingdom.

In Mario Party 8, on the board Koopa's Tycoon Town, if the player gets a three-Star hotel after trading coins with a Koopa Troopa at a hotel, the hotel looks like Mario's castle.

Trivia

 * The theme song of the Mario's castle stage is similar to that of the Battlefield in Super Smash Bros., while the player fights the Fighting Polygon Team. It is also similar to the P. 6-Finale song from Yoshi's Story.
 * The final area where Mario battles Wario seems to be the only part of the castle that is unfazed by Wario's spell. Evidence that supports this is the noticeable M designs on the windows, brick walls that have Super Mushrooms and Carrots on them, and a Mario statue in the part where the second phase of the final battle takes place.