The entrance area is a destroyed facility full of mirelurks and mirelurk hatchlings, along with dead raiders. In the center of the building is a large atrium with a hole in the middle that leads down into the partially flooded basement area. Drop down into the hole and one will see a pair of locked doors as well as a hallway off to the side. The hallway leads into a few rooms full of shelving and radioactive barrels, then eventually to a room with a fusion generator and a terminal. Activate the door locks via the terminal and the locked doors across the cavern will open. When dropping back down to the central area with the pool of water (or throw a grenade into the pool), a mirelurk queen will emerge. Before dropping down, grab the fusion core out of the generator.
Through the doors is a room full of radiation and then a hallway. The right hall leads to a room with another terminal, while the left leads to a room with frag mines and a safe, then a raider base. Note that the left hall also spawns a unique mirelurk encounter, with the mirelurk busting up the floor until finally emerging at the end of the hall. Continuing past the room with the mines and safe, there is a ramp leading up into the raider base. The base consists of several floors with a raider in power armor in a room near the top. The key to the locked Master door can be found in a metal box in the enclosed area behind the turret (around the corner from where the door is located).
Through the locked door is a room containing one or more raiders, as well as a sniper rifle and some ammo. The hole in the wall leads to a walkway above the statehouse atrium with the hole down into the sewers. Across the walkway is a room with one or two raiders, a turret, a steamer trunk, and an attack dog. One of the raiders is likely wearing power armor. In the room with the turret, there is a bookshelf with a mini nuke on it. In the corner is an elevator that heads back down into the entrance area.
In the building there is also a hidden room with a skeleton surrounded by three teddy bears. To get to the hidden room one must have a jet pack (or use the tcl command in console (pc) - walking on walls glitch will not work here). The hidden room is situated to the east, through a hole in the ceiling in the room leading onto the main area where the mirelurk queen spawns (on the middle floor). The hole one must enter is above the sloped floor where the ceiling has fallen in. Approaching the skeleton will trigger a chilling piano note.
- 掠奪者亞翠安的鑰匙 - 在掠奪者住處，砲塔後的一個封閉區域，金屬盒內。
- 逾期圖書 - 在有兩座獅子的大廳處通往的深處房間，靠在有著終端機的桌子。
- 核融合核心 - 在最底層，有著解鎖安全門的終端機的房間。
- 迷你核彈 - 在電梯附近的書架上。
- 掠奪者動力裝甲 - 在最終可以搭電梯下來的房間前，掠奪者老大身上。
- Vault-Tec lunchbox - In the room just before the raider commander and turret due east of the table with three chairs and a bunch of loose caps on top.
- Day Tripper - In the northwest corner of the room that the elevator lowers to - tucked behind the bookshelf.
- 州議會大廈筆記 - 在二樓一個房間內拾荒者屍體上。
- Without a jet pack, once the player jumps down the large hole in the atrium to the large pool at the bottom, the player will be forced to advance their way through the mirelurk infested basement and upward through subsequent raider base in order to be able to exit the State House. Players wishing to exit ASAP will not be able to do so until they reach the catwalk that is across the upper side of the atrium and then drop/jump down to the lower edges of the hole. Survival players should take note that there are no beds to sleep in from the pool area until the end of the raider base.
- The mirelurk queen will only spawn once the metal doors have been unlocked via the terminal near the fusion core generator and afterwards the player either approaches the pool proximate to the terminal to the north or the player throws an explosive into the pool. Players who wish to avoid the mirelurk queen altogether can safely access the unlocked hallway by returning to the pool area via the mostly irradiated path leading up to the terminal.
The Massachusetts State House appears only in Fallout 4.