Anteroom

From the Super Mario Wiki

The Anteroom is the second room Luigi explores in Luigi's Mansion; it is located in the first area. The Anteroom resembles a short hallway and is where Luigi first encounters Purple Punchers.

After Luigi entered the Anteroom from the Parlor, the doors were blocked with force fields, trapping the green plumber inside the room. He was then attacked by several Gold Ghosts. After dispatching these ghouls, Luigi was attacked by a few Purple Punchers, who proved to be much more powerful than their weaker cousins. However, the brave plumber managed to dispatch them. When all the ghosts were captured, the force fields disappeared and Luigi continued his adventure into the Wardrobe Room.

The Anteroom is probably the blandest room in the game, having nothing but vases on tables inside.

The Rooms in Luigi's Mansion
Area One
Foyer | Parlor | Anteroom | Wardrobe Room | Balcony | Study | Master Bedroom | Nursery
Area Two
Bathroom | Ball Room | Storage Room | Washroom | Mirror Room | Laundry Room | Butler's Room | Hidden Room | Conservatory | Dining Room | Kitchen | Boneyard | Graveyard
Area Three
Courtyard | Bottom of the Well | Rec Room | Tea Room | Bathroom | Billiards Room | Projection Room | Washroom | Nana's Room | The Twins' Room | Astral Hall | Observatory | Fortune-Teller's Room | Safari Room | Balcony
Area Four
Telephone Room | Breaker Room | Cellar | Clockwork Room | Roof | Sealed Room | Sitting Room | Guest Room | Armory | Ceramics Studio | Pipe Room | Cold Storage | Artist's Studio | Altar