Treacherous Mansion

Treacherous Mansion is the final and longest mansion that Luigi visits in Luigi's Mansion: Dark Moon. It has a museum theme. It is also the location of the final Dark Moon piece. Many rooms on the first floor of Treacherous Mansion are based off of the previous mansions in the game. Also, almost every ghost that Luigi encounters appear here. King Boo comes to this mansion to open a Paranormal Portal to unleash all of the undead to create his army.

History
Treacherous Mansion is an abandoned Museum positioned right in the middle of a giant ravine, which becomes cut off from land access after Luigi reaches the front steps. According to E. Gadd, the mansion contains artifacts and items from Evershade Valley and beyond making it the most "precious" of the mansions. The Mansion is slightly changed to a more spooky feel after King Boo arrives. It is called the Treacherous Mansion as it could collapse into the ravine below. It however does not at any point.

In-Game Description
''This massive mansion is filled with exotic exhibits created by its late globe-trotting owner. Oh, and it also contains the strongest paranormal signals ever recorded!''

''This massive mansion is filled with exotic exhibits fashioned by its globetrotting late owner. Oh, and it also has the strongest paranormal signals ever recorded!'' (PAL version)

Treasures

 * 13 Diamonds
 * Keys

Bosses

 * Mini-bosses:Big Boo, Strong Poltergeist
 * Bosses:Tough Possessor (possessing suits of armor)

First Floor

 * Veranda
 * Front Entrance
 * Inner Courtyard

First Floor West Side

 * West Gallery
 * Dark Age Exhibit (Dark Ages Exhibit in PAL version)
 * Grand West
 * Kitchen
 * Ice Age Exhibit

First Floor East Side

 * East Gallery
 * Jungle Exhibit
 * Grand East
 * Restrooms (Toilet in PAL Version)
 * Ancient Exhibit

Second Floor

 * Inner Courtyard
 * Terrace

Second Floor West Side

 * West Corridor
 * West Balcony
 * Dark Age Exhibit
 * Space Exhibit
 * Archives
 * Aviation Exhibit
 * Ice Age Exhibit

Second Floor East Side

 * East Corridor
 * East Balcony
 * Jungle Exhibit
 * Nautical Exhibit
 * Study
 * Train Exhibit
 * Ancient Exhibit

Third Floor

 * Gargoyle Roof

Basement 1

 * Veranda
 * Bottom of Well
 * Guard Tunnel (Guarded Tunnel in PAL Version)
 * Ceremonial Chamber
 * Cliffside
 * Jungle Exhibit
 * Ancient Exhibit

Basement 2

 * Dungeon Cells
 * Haunted Catacombs
 * Underground Lab
 * Cliffside

Basement 3

 * Dungeon Cells

Trivia

 * This is the only mansion in the game that requires Luigi to open one door as the rest of the doors are already unlocked.
 * This is the only mansion besides Gloomy Manor that has multiple music tracks, the track changes whenever Luigi looks through a window or crack in the wall.
 * Oddly it is called a "Mansion" instead of a "Museum".
 * The bottom four exhibits in the mansion are based on the four previous mansions in the game in some way:
 * The Dark Ages Exhibit represents Gloomy Manor due to the knights found in the manor.
 * The Jungle Exhibit represents Haunted Towers due to both having vegetational designs.
 * The Ancient Exhibit represents Old Clockworks due to the latter having Egyptian like basement.
 * The Ice Age Exhibit represents Secret Mine due to both having icy themes.