World 1-4 (Super Mario Bros.)

World 1-4 is the final course of World 1 in Super Mario Bros. It is the first castle course of the game and the series. A Bowser Impostor is encountered at the end, which is actually a Goomba in disguise.

Layout
The player starts the level on an elevated area with stairs heading downwards, ending at a pit of lava. Afterward is a platform with a Fire Bar and surrounded by lava, with a ? Block containing a power-up above it. After a corridor of Fire Bars on the ceiling, there is a room with more Fire Bars placed on both the ceiling and the floor. Next is a room containing several Hidden Blocks before the bridge with the Fake Bowser, which has a horizontally moving lift above.

Super Mario Bros. Deluxe challenges
In Super Mario Bros. Deluxe, the player can collect five Red Coins, find a hidden Yoshi Egg, and get a medal based on their score. The Yoshi Egg is found in the top-middle Hidden Block in the larger empty space with the other Hidden Blocks before the Bowser Imposter, and the score to beat is 13000. The Red Coin locations are: Additionally, the Toad at the end of the castle is replaced with a door to the end results area.
 * Above the level's ? Block
 * In the hallway with the Fire Bars
 * Red Coins three and four are in the proceeding area, between the Fire Bars
 * Above the Bowser Imposter

Enemies

 * Fire Bars: 7
 * Bowser Impostor (boss)

Level statistics

 * Power-ups: 1 (Super Mushroom or Fire Flower)
 * 1-Up Mushrooms: 0
 * Secret areas: 0

Trivia

 * The level and the boss fight has been re-created in Super Mario Advance 4: Super Mario Bros. 3 as Classic World 1-4, and in New Super Mario Bros. 2 in the Gold Classics Pack from Coin Rush on the final course along with World 1-1 from said game.
 * World 6-4 is the same as this level, but with more Fire Bars and Lava Bubbles added.

Mondo 1-4 (Super Mario Bros.)