The Castle

The Castle, also known as Fort Independence, is a location and potential settlement in the South Boston neighborhood of Boston

Background
A historic landmark in the Boston area, the pre-Revolutionary location is now referred to as the Castle. It served as the headquarters for the Commonwealth Minutemen until 2240, when the castle was overrun by a sea creature. Their general at the time, McGann, was cut off from the battle early on when the tunnel to his quarters collapsed. While waiting for rescue, he secured the armory by activating its security. Eventually, as he ran out of supplies (and conceded that help was not coming), he drank wine he found, easing his passing into oblivion.

Layout
Fort Independence is a star fort, consisting of five triangular bastions connected by walls. The walls are hollow and contain most of the fort's infrastructure, with only the workshop and the Radio Freedom transmitter in the courtyard and two ruined Minutemen artillery positions on top of the wall. The northwest and southwest walls have been all but demolished, and a sizable hole punched in the south wall as well, making the west bastion, which contains the armory, inaccessible except through the tunnels. The north bastion contains the kitchen, the east bastion contains the general's quarters and access to the tunnels, and the southeast bastion contains the barracks. The southwest bastion is completely inaccessible.

The Castle is initially occupied by a large group of mirelurks, and piles of mud studded with mirelurk egg clutches can be found all over the courtyard and all interior areas save the armory. Once the quest Taking Independence is completed, these will be cleared away and the fort made available for settlement.

Inside the fort is a missile launcher and flamer, as well as a small amount of ammunition for each. Once settled, it comes with five free beds, a cooking stove, a first aid station, a chemistry station, starter lighting and an electrical cable system, and an industrial water purifier good for 40 units of water should the player character reintroduce power into the system.

Inside the armory are a cache of heavy weapons, a weapons workbench and an armor workbench, and three laser turrets as well as three Tesla arcs that can be stored or redeployed elsewhere using the workshop menu. Also present are laser musket mods and the schematics for building the special artillery units. However, access to the armory is impossible until the quest Old Guns is completed.

Access to the settlement is through the south via the main gate, and enemies will usually attack from this direction or the other land approach to the northwest; behind the main gate is a small and highly defensible room.

The Castle tunnels
The entrance to the tunnels is difficult to find prior to beginning the quest Old Guns. It is hidden behind rubble, and cannot be accessed unless the workshop for the Castle has been unlocked by advancing in the quest Taking Independence.

Once the workshop is unlocked, head to the room in the east bastion. Then, look to the left to find a pile of rubble which can be scrapped in workshop mode. Upon scrapping this rubble, the stairs leading down to the door to the Castle tunnels will be revealed.

The tunnels are winding but essentially linear. Hazards include mines, explosive gas, radiation, and a turret. Storage areas are encountered first, then an area with a chemistry station and a generator, followed by a barracks with usable beds. Next is a locked security door guarded by a malfunctioning, hostile sentry bot named Sarge; this door can only be unlocked by Ronnie Shaw via the nearby terminal during the quest Old Guns. Behind the door is a room with the corpse of General McGann and the exit to the armory in the west bastion.

Settlement information
The Castle's courtyard is spacious, with plenty of room for growing crops or constructing buildings if desired. There is also accessible open water to the north (outside the walls of the fort) which can be useful for large-scale water production. Being a fort, the Castle is already well-fortified from attacks, which is helpful given that the area is prone to raids. There is almost no junk that can be scrapped for building materials, so supply lines will likely be needed to supplement the Castle's resources. The tunnels can be useful as an initial source of extra junk.

Inhabitants

 * General McGann
 * Up to five Minutemen, including radio operator (optional)
 * Ronnie Shaw (optional)
 * Sarge

Notable loot

 * Guns and Bullets issue #8 - On the radio operator's desk, in the middle of the Castle courtyard.
 * Fat Man and mini nuke - In the armory, accessible during/after Old Guns.
 * Nuka grenade - In the armory, accessible during/after Old Guns.
 * Various laser musket upgrades - In the armory, accessible during/after Old Guns.
 * The Last Minute - Sold by Ronnie Shaw, after completing Old Guns.
 * Bottle message #2 - Outside the southeast bastion, by the water's edge. The submerged boat and steamer trunk for the objective are located just northwest of Spectacle Island.

Related quests

 * Taking Independence: The Sole Survivor can retake the fort by wiping out the mirelurks that have since made it their nest. They can clear out the egg clutches and corpses and reactivate their communications equipment.
 * Old Guns: Ronnie Shaw, a member from before the Castle's loss, calls the Sole Survivor back to open its west bastion and access its armory, giving the Minutemen access to their artillery.

Appearances
The Castle only appears in Fallout 4.

Behind the scenes

 * The Castle is based on the real-world Fort Independence, which is located on Castle Island.
 * To the west of the location is a partially destroyed building, which has a destroyed sign that reads "IVANS" with a shamrock next to it. This is a reference to the real-world restaurant called "Sullivan's," with the sign looking identical to the one used by the restaurant in 1963.

Bugs

 * The Minuteman in charge of broadcasting Radio Freedom may complain (usually after starting the Old Guns quest) that the transmitter is not being powered, despite having power. This is due to the Minuteman becoming hostile to Sarge in the Castle tunnels, and so should be able to be prevented by eliminating Sarge before Old Guns. Otherwise, this bug prevents the use of Radio Freedom.
 * You can get into the armory without Ronnie Shaw and before Old Guns has been started by walking up to the door and placing a fast-travel marker underneath.
 * Assigning guards to guard towers can be problematic, as they assign to a patrol route along (invisible) patrol markers that are already in place when you take the Castle.
 * When building generators to power the beacon, the beacon will show the power requirement not being met regardless of how much power is being supplied to it, and as a result will not activate.
 * This can usually be fixed by removing each generator, storing them, and replacing them.
 * Sometimes the castle door will not open, forcing the player character to go back through the tunnels.