World 1-4 (Super Mario Bros.)

World 1-4 is the final course of World 1 in Super Mario Bros.. It is a castle course and the False Bowser found in the level is actually a Goomba.

Layout
Mario starts the level on an elevated area with stairs heading downwards. There is a gap with lava and, right after it, a block. There are also two lava gaps with a Firebar on the platform between them. It contains a Question Block with a Fire Flower in it. Past it, a corridor with three Firebars must be crossed. Mario reaches a room with three Firebars, two on the floor and one on the roof, along two blocks. He, then, finds another room with six hidden blocks. In this area, False Bowser's fireballs start to appear. Mario can use a gap to avoid these fireballs and then, the False Bowser is seen on a bridge with a small platform moving from side to side right above him. If Mario gets past the False Bowser by either using the platform or running under him and touches the Ax, the bridge collapses, causing him to fall into the lava. A Mushroom Retainer is saved and Mario gains access to World 2.

Trivia
The level and the boss fight has been re-created in New Super Mario Bros. 2, in Gold Classics Pack from Coin Rush.