Guard Tunnel

The Guard Tunnel is a room in Treacherous Mansion in Luigi's Mansion: Dark Moon. Accessible from the Bottom of Well to the west and the Cliffside to the east, it's an underground passageway lined with suits of armour that plays an important part in mission E-1.

History
In E-1: Front-Door Key, the Guard Tunnel is visited by Luigi in his chase after the Polterpup that has stolen the mansion's front door key. When he tries to pull down the right wall with the vine here, he has to fight some Strong Greenies and Strong Slammers to continue his journey.

In E-2 to E-5, the Guard Tunnel is unable to be visited along with most of Treacherous Mansions basement.

In E-Bonus: Terrifying Invasion, the Guard Tunnel can be visited again but has nothing of interest.