World 1 (New Super Mario Bros. Wii)

Mushroom Plains is the first world in New Super Mario Bros. Wii, consisting of six levels, a fortress, a castle and a boss, as well as three special stages, which are accessible by entering the Mushroom Houses, as well as housing Peach's Castle. There are three special stages, two reds and one gold; the two reds occurring upon completion of World's 1-2 and 1-4, and the gold mushroom house occurring upon completion of World 1-3.