How to clear Bowser's Castle Back Door in Super Mario World for the Super Nintendo Entertainment System and Game Boy Advance.

How to Clear Bowser's Castle Back Door
Go to the right and hit the red ? Block to turn on a spotlight that swings slightly left and right.
At the top of the stairs, there is a Ninji that jumps up and down. Stomp on it, then go past the lava pit down below.
There is a Ninji, followed by a Mechakoopa going through a narrow passage on the right.
After that, there are two Ninjis, a Mechakoopa in a narrow passage, and two more Ninjis, followed by a lava pit.
After that, if you skipped the castle front door and entered through the back door, you will find a Midway Gate.
Go to the right and go through the big door to face the final boss, Bowser Koopa!