The Gallery is one of the many rooms in E. Gadd's Lab, and found by Luigi, first appearing in Luigi's Mansion. It is a room that is located in Professor Elvin Gadd's laboratory. It is the place where one can see the frames of his captured gallery ghosts. It has two hallways, and each hallway leads Luigi to a room with the ultimate portrait of King Boo. It contains two statues of angels, which they will flap their wings if they are examined with. A picture of Luigi's NEW Mansion will also appear on the left wall after completing the gameplay walkthrough.
Professor E. Gadd stands in front of a door in the Gallery. The room that this door leads to is the Ghost Portrificationizer room, according to the Game Boy Horror, but it can't be entered because Professor E. Gadd is standing in front of it and is blocking it.
The beta version of the gallery was much larger, meaning there were most likely more Portrait Ghosts in the beta version than in the final version of the game.