World 1 (Super Mario Bros.)

World 1 is the first world in the game Super Mario Bros., located in the Mushroom Kingdom.

World 1-1 contains the basics of the Super Mario Bros. game, getting the player ready for the journey ahead. The level consists of Super Mushrooms, standard enemies such as Goombas and Koopa Troopas, a lot of Coins, a hidden secret bonus area that will allow the player to skip most of the level, Fire Flowers, deadly pits, and a flagpole at the end.

World 1-1 starts out on a brick path. As Mario moves forward, a Goomba appears and starts walking toward Mario. The red-clad plumber also reaches the first Question Block of the game, and afterward the six block triangle formation of ? Blocks and regular brick blocks (with a Super Mushroom inside the left block). A set of Pipes await Mario with Goombas located in between the plumbing. The final pipe among the set leads to a bonus area of coins and can be entered to bypass much of the level. After that, assuming the pipe was not taken, there is a gap followed by another Question Block containing an item, possibly a Super Mushroom or Fire Flower, depending on Mario's health. Additionally, Goombas start falling down from a long row of blocks above.

Afterward, a block down below contains ten Coins that Mario can retrieve by Jumping repeatedly underneath the brick. Then there is a notable ? Block triangle formation, which contains no regular blocks. The top block contains a Fire Flower (or a Super Mushroom if Mario is small). Upcoming are some more Brick and ? Blocks, followed by a pyramid-like set of unbreakable blocks with a gap in the middle. After that is another set of unbreakable blocks, this time with a gap in the middle that Mario can fall into and get killed. Just following is another pipe that cannot be entered, accompanied by two Goombas and a set of ? Blocks with coins inside.

Lastly, Mario reaches the ending staircase for the level, and the Flagpole afterward, which is reused in all underground and underwater stages in the game.

The original World 1-1 from Super Mario Bros. has been re-created in many games, including Super Mario Advance 4: Super Mario Bros. 3, and Super Smash Bros. Brawl, where it appears as a stage named Mushroomy Kingdom in which it is an old desert, rather than a grassland. The stage is also notable for containing the first extra life item in the history of gaming, the hidden 1-Up Mushroom.

This is the first underground level in Super Mario Bros, and is also the first appearance of Piranha Plants. Mario/Luigi starts the level by falling through a hole in the roof by a pipe. There will be two Goombas and five Question Blocks. The first one contains a Super Mushroom or Fire Flower, the other four ones contain coins. There will be a block tower structure, where there's a Goomba and a Brick Block with 10 Coins. Ahead, there will be some Brick Blocks, one of them containing a Star and some Coins, with two Koopa Troopas underneath them. The player will reach a place filled with Brick Blocks with a Koopa Troopa and five Goombas. There will also be a Brick Block with a Super Mushroom or Fire Flower and a masked Brick Block with ten Coins. There will be a Pit and, after it, a Block platform that allows Mario to get an 1-Up Mushroom. Mario/Luigi will find two Goombas and three pipes, all of them containing Piranha Plants. The player can enter in the first Pipe, that will lead him/her to a room with Coins and a 10-Coin Brick Block. Mario can exit the area by a Warp Pipe in the extreme right. This pipe will lead to the third one in the main area. There will be two gaps and, between them, two ground blocks and some Brick Blocks. After that, a small, half-pyramid structure with two Goombas is seen. Ahead, a group of platforms will be rising and falling. Between them, a Koopa Troopa and some Brick Blocks. The player will reach a Pipe that will lead them to the final area. He/she can use the platforms to reach a Warp Zone hidden through the roof. From right to left, the first pipe will head to World 2, the second one will lead to World 3, and the third one will lead to World 4. If the player goes through the regular level pipe, they will lead Mario/Luigi to a pipe with a Piranha Plant in an overworld area. There will be a Block half-pyramid that allows Mario/Luigi to jump on the top of the Flagpole.

This level has also been recreated in Super Smash Bros. Brawl, as an alternate Mushroomy Kingdom. There is a chance this stage will be played instead of the area based off of World 1-1.

Through a small ground area, Mario will reach a giant mushroom that can be used to reach two more mushrooms, containing a Koopa Troopa and three coins. Ahead, three mushrooms are used by two Goombas. On the top of the third and taller mushroom, a shorter mushroom can be reached. There will be a platform that can help Mario to reach the top of a tall mushroom with four Coins. Under this tree, a shorter one contains the only Question Block of the level that contains a Super Mushroom or a Fire Flower, depending on Mario's form. There will be a short mushroom and a taller one, that is used to reach a tall mushroom that contains a Goomba. Between these two mushrooms, there's a Koopa Paratroopa. There will be two platforms that will go side to side. There will also be some Coins. There will be two mushrooms, the first one is small and of medium width, while the other is wide and tall. There will be a Koopa Troopa in the taller one. A short mushroom with three coins is under a Koopa Paratroopa. There will be two similar mushrooms that can be used to reach a platform. The platform can help Mario to reach a Block wall. The Flagpole will be after it.

This level was recreated in World 5-3, with some elements added. The idea of a stage based on jumping across giant mushrooms would become a recurring trend in the series.

Mario will start the level in an elevated area with block stairs heading downwards. There will be a gap with lava and, right after it, a Used Block. There will be two lava gaps, with a Firebar in the ground between them. There will also be a Question Block with a Fire Flower. Past it, there will be a corridor with three Firebars. Passing through it, Mario will reach a room with three Firebars, two on the floor and one on the roof, along two Used Blocks. Mario will reach a room with six hidden Blocks, when the False Bowser's fireballs start to appear. Passing through a gap with a bottom, used to escape from the fireballs, Mario will reach a False Bowser (actually a Goomba) on a bridge and a small platform moving from side to side above it. If Mario jumps over the False Bowser using the platform and touches the Ax, the bridge will collapse, causing the False Bowser to fall into the lava. A Mushroom Retainer is saved and Mario gains access to the World 2.

Levelmaps
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Super Mario Bros.
File:Mario Bros. World.png|World 1-1 File:Falsebowser1-4.jpg|Battling the False Bowser in World 1-4 File:SMB Toadsez.png|Rescuing the Mushroom Retainer in World 1-4 File:SMB Warpzone.png|The Warp Zone in World 1-2

Super Mario Advance 4
File:W1-1SMA4e.PNG|World 1-1 File:W1-2SMA4e.PNG|World 1-2 File:W1-3SMA4e.PNG|World 1-3 File:W1-4SMA4e.PNG|World 1-4

Trivia

 * A license plate in the Mario Kart: Double Dash!! course Mushroom City has "W 1-1" written on it. This is a reference to World 1-1. Some players have been confused that this is supposed to say 'Wii', despite that the Wii was released three years later. The same license plate has been spotted on Moonview Highway.
 * Several sections of Lineland Road in Super Paper Mario are modeled after those of World 1-1. Also in Super Paper Mario, in Chapter 3-1 there's an underground section almost identical to World 1-2, but the Warp Zone leads to other parts of the area, not other worlds.
 * World 1-1 and World 1-2 have been ported to the Super Smash Bros. Brawl stage, Mushroomy Kingdom. These levels have been recreated to make them look old and barren since Super Mario Bros. launched in 1985 and Brawl in 2008.
 * When playing as Bowser in Paper Mario: The Thousand Year Door, Bowser will enter Worlds 1-1, 1-2, and 1-3.
 * All levels in this world were released as card levels for World-e in Super Mario Advance 4: Super Mario Bros. 3. However, only World 1-1 was released outside of Japan.