Mario Bros. (stage)
From the Super Mario Wiki
In the debut game, the sewers was the only location in the entire game, much like many other 2D platforming games. The Mario Brothers Plumbing, or to put it simply, Mario and Luigi were called into service after reports of odd-looking monsters such as big turtles, big, angry crabs, enormous flies and weird ice-blocks appearing in the sewers of Brooklyn, New York. It seems like the Mario Bros. found a way to the Mushroom World in the sewers. Oddly, there are also coins and POW Block in the sewers. In the remakes (more specifically, the Super Mario Advance series and Mario & Luigi: Superstar Saga), the big turtles were replaced with spiked turtles, and Bowser also makes an appearance as an obstacle in one of the variants of the stage, further hinting that the Mario Bros. found a way to the Mushroom World there, as well as a possible reason.
In Mario Power Tennis, the stage appears in the form as the Mario Classic Court.
The Mario Bros. stage made a cameo in Tetris DS - it appeared in the background of the Nintendo DS's top screen if the player chose any mode besides Records.
Mario Bros. is included in Super Smash Bros. Brawl as an unlockable stage. It is a recreation of how the location appeared in the original game and features elements from that game as well, such as enemies and POW Blocks. This is notably the first time that the location from Mario Bros. was called by a name.
In the Coin Battle mode, the first stage's beginning is very similar to the Mario Bros. stage. Characters can still walk to the left and appear at the right, and vice versa, just like the original stage. The only differences in this area are the design, the POW Block being on a platform instead of floating in mid-air, and coins, ? Blocks and Koopa Troopas have been added to the area. In order to continue the stage, the characters must enter the pipe at the top-centre of the area.