4 Ludwig's Castle

#4 Ludwig's Castle is the final level in the Twin Bridges area of Super Mario World. It consists of a maze-like small-roofed area, a spike escape, fences with Koopa Troopas climbing them, and a boss fight with Ludwig von Koopa. After Mario defeats Ludwig, he retrieves the imprisoned Yoshi (which is trapped in an egg), and attempts to blow up the castle. However, the detonation causes the castle to rocket into the air, and it crashes into a nearby mountain.