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The Ballroom is a room in The Last Resort in Luigi's Mansion 3. It is accessed by going through the big door at the top of the Grand Lobby's steps. The room is very spacious and has tables, stacks of chairs, and a trash can stationed by the wall on the right. There is some money on the chairs and in the trash. The walls are lined with lights, and there is a chandelier on the ceiling that can be spun using the Poltergust G-00, which opens the left wall to reveal a hidden area.
The hidden area has a table in the center with a plate, a drink, and a red gem on it. There are chairs and other tables in the room with sheets over them; Luigi can remove the sheets and vacuum the tables and chairs to reveal money. Cushions are scattered around the front end of the room. A plant sits on a stand next to the window on the left.
When Luigi comes here for the first time, he finds Professor E. Gadd trapped inside a painting at the back of the room. However, he is unable to release him at that time. He must go to the Storage Room and get the Dark-Light Device before he can free him.