World 2-4 (Super Mario Bros.: The Lost Levels)
From the Super Mario Wiki, the Mario encyclopedia
The player starts at the top of some stairs, which lead into a passage the player needs to jump through, avoiding the Koopa Troopa above. The passage ends at a drop into a lava pit, which the player needs to avoid by moving right as they fall. After a row of Goombas and Koopa Troopas, there is a Fire Bar before a lava pit with a set of stairs across it, above which and against the wall is a Hidden Block with a power-up. Next is a hallway split between an upper and lower path, the top contains more Fire Bars and the bottom contains small lava pits, and a Lava Bubble jumps between both. After the hall are large lava pits with Fire Bars between them and Lava Bubbles jumping out of them before the Fake Bowser.