Bowser's Sky Castle

Bowser's Sky Castle is World 6-3, and the final level, of Paper Mario: Sticker Star.

History
The massive castle floats in the sky, and is where Bowser, and by extension the final Royal Sticker, resides. However, Mario only explores a few rooms.

The first room is a long hallway. Mario opens the large door at the end and encounters Kamek, who battles him. After he is defeated, he finally dies, and Mario continues onward.

The next room contains a strange carpet that is full of gaps and holes, and begins rolling itself up once Mario steps on it. After making it to the other side, Mario sees Princess Peach, taped to a chain. Before Mario can peel it off, Bowser appears, transforms the room into a huge hallway, and challenges Mario.

By the time Mario finishes Bowser off, the castle seems to have been mostly destroyed. As the game then cuts to the Sticker Fest, the castle's outcome is unknown.

Bosses

 * Bowser
 * 3 random enemies
 * Whomp
 * Podoboo
 * Chain Chomp
 * Kamek

Trivia

 * The entire level has no background music, only thunder effects and echoes when Mario moves. This is likely done as part of the atmosphere.
 * It is the only time in the series where the castle contains no regular enemies and instead only bosses, save for those assisting Bowser.
 * The castle's level marker stays red even if the player completes the game. Strangely, it is shown blue on the Prima guide.