World A-1

World A-1 is the first level of World A in Super Mario Bros.: The Lost Levels and the fifth secret level overall in said game.

Layout
In the first group of ? Blocks with Koopa Troopas, there is a Hidden Block with a power-up between the ? Blocks on the top row. In the next group of Brick Blocks with Koopa Troopas, in the far right block on the top row is a Beanstalk that leads to Coin Heaven, the end of which will drop the player onto a platform with a 1-Up Mushroom above it. If the player does not go through Coin Heaven, they will have to jump through pipes with Piranha Plants. After either path are two charging Hammer Bros. on two rows of ? Blocks, the third block from the right on the bottom contains a Poison Mushroom. Next are rows of Brick Blocks with Koopa Troopas, followed by a pipe with a Piranha Plant, and a row of ? Blocks with the second from the left containing a Poison Mushroom. Afterward are two charging Hammer Bros. jumping between rows of Brick Blocks, and a Warp Pipe on the top row will take the player to an underground area with Coins, a power-up, and a Poison Mushroom. Past the Hammer Bros. is a platform with Koopa Paratroopas, below which is the exit pipe from the underground area, and the end block of the bridge contains a power-up. Through a grounded and hanging pipe with Piranha Plants is a Springboard between several narrow platforms with Koopa Troopas, above the second of which is a Coin Block, before the Goal Pole.

Trivia

 * The title card for this level depicts a Red Koopa Paratroopa, though none appear in the level. The title card also does not have a Hammer Bro. although there is space to fit in.