Professor Elvin Gadd's Lab
From the Super Mario Wiki
Not to be confused with The Lab, the main lab room inside E. Gadd's home in Luigi's Mansion.
Professor Elvin Gadd's Lab is the home of Professor Elvin Gadd. The lab used to be much smaller when it was located on Thwomp Mountain (as seen in Mario & Luigi: Partners in Time); however, after the volcanic eruption destroyed his lab, he moved to a new and improved location in Boo Woods.
The lab first appears in Luigi's Mansion. It contains a Gallery which used to house all of the ghosts which haunt Luigi's Mansion before the events of the game. In addition, it also has a laboratory, a Ghost Portrificationizer, and a Training Room.