World 1 (New Super Mario Bros. Wii)
From the Super Mario Wiki
World 1 is the first world in New Super Mario Bros. Wii. World 1 is owned by Larry Koopa, the first boss to be fought in the game. This world features typical grassy plains with many colorful mushroom hills, similar to New Super Mario Bros. It has eight levels, three Toad Houses, and a cannon.
 Level Information
 Level Previews
 New Enemies