Luigi's Mansion is a huge mansion that Luigi won in a contest in the GameCube's Luigi's Mansion. Luigi had to use a Poltergust 3000 to suck up Boos, Portrait Ghosts, and other ghosts, all in order to find Mario, who got kidnapped by the ghosts.
In some part of the beginning, Professer Elvin Gadd was sucking up ghosts until Luigi came in the room and saw him.
In Super Smash Bros. Brawl, this stage is one of the states that during all star mode, Mario, Luigi, Peach, and Bowser can appear on to fight. In it, there are three levels in the mansion, and each can break if repeatedly attacked.