World 1 (New Super Mario Bros.)

The World 1 in New Super Mario Bros. was around Princess Peach's Castle. It had many grass, and flowers and here was where Mario and Luigi's adventure started. This world takes place in the Mushroom Kingdom.

Bowser Jr. was fought here for the first time, and Bowser was the first boss in the game, not counting Bowser Jr. who's a mini-boss. Afterf defeating Bowser, the brothers would go to World 2.