World 1 (Super Mario Bros.)

World 1 is a world in the Mushroom Kingdom in Super Mario Bros. It is the first world in the game.

World 1-1
The original World 1-1 from Super Mario Bros. has been re-created in many games, including Super Smash Bros. Brawl, where it appears as a stage named Mushroomy Kingdom. In Super Smash Bros. Brawl, World 1-1 is an old desert, rather than a grassland, like it is in most games. 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, Fire Flowers, deadly gaps, and a flagpole at the end.

World 1-1 starts out on a brick path, possibly a path that was once a walkway in a town of the Mushroom Kingdom before King Bowser's violent coup. As Mario moves forward, a Goomba appears and starts walking toward Mario. The red-clad plumber also reaches the the memorable first ? Block and then 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 warp through the level. After that, there is a gap followed by a ? Block containing a Fire Flower inside. 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 (at the right time) underneath the brick. Then there is the notable ? Block triangle formation, which contains no regular blocks. The top block contains a Fire Flower (or a Super Mushroom if Mario is regular instead of Super Mario). 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.

World 1-2
This is the first underground level in Super Mario Bros. It starts out with Mario or Luigi going through a pipe in the over world. They go underground until the end of the level when they get out and jump the flagpole. Since it's dark underground, the Goombas are blue. Also it is the first time the player can go to a Warp Zone.

World 1-3
This level of the game is the first one to be set at the heights. The player must jump across many high tree-like platforms in order to complete this level. The level contains only three types of enemies: Goombas, Koopas, and Koopa Paratroopas. As the player progresses in the level, he or she must eventually jump across orange platforms; these platforms quickly sink through the if the player stands on them for too long. Eventually, the player will reach low ground where a staircase leading to the flagpole is located.

Only one ? Block can be found in the entire level, while there aren't any warp pipes in any location of the level. This level is later reused in World 5-3, only with some elements altered to make the level more difficult.

World 1-4
This is the final level of World 1, and the first level to take place in a castle. The player must jump across a few pits of lava and avoid a few firebars in order to progress successfully through the level. This castle is fairly short in comparison with other castle levels, so before long, the player will encounter some Bowser's fireballs. As the player jumps up to the bridge, he or she will encounter a False Bowser. The player can defeat the False Bowser by either repeatedly throwing fireballs at it, or by pressing the axe behind him, thus collapsing the bridge. The player will then have rescued a Mushroom Retainer, gaining access to World 2.

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.
 * 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 it 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, 1-3, and 1-4.