World 9-3 (Super Mario Bros.: The Lost Levels)

World 9-3 is the third level of World 9 in Super Mario Bros.: The Lost Levels and the third secret level overall in said game. This is the only level in the game that is set in the overworld, but has a castle color scheme and music theme. In Super Mario All-Stars, however, it uses castle interior tiles with a brown color palette.

Layout
The level is a long structure, devoid of any enemies or obstacles other than Bowser's Brother before the flagpole. There is a Springboard near the start of the level that can help the player get on top of the structure's ceiling. Soon after the Springboard is a Brick Block containing a Beanstalk that leads to Coin Heaven; a Warp Pipe later on will also take the player to Coin Heaven.

Trivia

 * This level's Coin Heaven is the only one in the game without a scrolling platform, leaving the player free to collect all the Coins at their leisure.
 * Since Bowser's Brother looks identical to Bowser instead of being a blueish look-alike in Super Mario All-Stars, there is no indication that he is not the actual Bowser in that version.
 * The fact that Mario completes the level by reaching the flagpole after defeating Bowser's Brother would later return in Super Mario 3D Land and Super Mario 3D World, where all levels, including those with bosses, end with the player reaching the Goal Pole to complete it rather than simply exiting shortly after the defeat of a boss.