Super Mario World/Larry's Castle

The final level before you enter the Front Door of Bowser's Castle, is Larry's Castle.

Walkthrough
Ride a Snake Block that will move in multiple directions, including up! The best thing to do is stand very close to the right, although not too close. This will ensure that you have a little head-start. The Snake Block moves all over the place, so watch the timer. Beware of all the that you will encounter along your travel. If you go directly down a secret path, you will find a check-point before a second door to Part 2.

You will find many in this area that serve as an enemy, but can still destroy the walls that block your way. Watch out for rising and falling spikes in a narrow path before the red door.

BOSS: Larry Koopa
The boss battle with Larry is just like the setting of the first boss battle with Iggy Koopa; there is a tilting platform where Mario must jump on Larry to push him into the surrounding lava below. But this time, there are jumping fireballs to the left, center, and right of the platform to avoid, making things a lot harder. As with Iggy, fireballs will also push Larry towards the edge, and the Cape Spin will have no effect.