Mount Desert Island Naval Facility, had, as all bases do, a control room or "brain" of the facility. It is likely Arnold Wabash, Captain of the USS Democracy, used this place to receive orders for his ship. When DiMA found the facility, he hid his memories in one of the control consoles out of guilt. As the Children now control the base, they know not to enter this part of the facility, as anyone who does doesn't come back.
Upon entering the command center from The Nucleus, you will be in a hallway with red alert lights & alarms flashing. The hall ahead will have numerous laser tripwires that move vertically along the wall. There is a room to the right of the entrance, which leads to a utility tunnel and - ultimately - a dead-end room with some junk loot and a weapons bench.
After the first hall with the lasers, you'll enter a rocky tunnel with a turret on the wall at the bend. As the tunnel turns left, watch out for another turret on the wall ahead as well as possibly a Mr. Gutsy. This area also contains some barracks rooms to the left and a facilities announcement terminal.
Another rocky tunnel leads you beyond the barracks into a kitchen area containing at least one protectron on patrol. Proceeding past the kitchen/cafeteria area and up the stairs will take you through a longer tunnel, the end of which contains multiple leveled robots & two wall-mounted turrets. At that point, you'll find a security gate with a terminal on one side and a door on the other side leading back to The Nucleus. The room also has a trunk in the corner.
Opening the security gate will grant access to the terminal needed for Best Left Forgotten. Before you can use the terminal, you must enter the fenced-in area and activate the circuit breaker on the back wall. Doing so will sound an alarm and release a hostile assaultron from behind the metal door.