Vault 75

Vault 75 is a Vault-Tec Vault located in the Commonwealth in 2287.
Background Located underneath the Malden Middle School, this Vault was presented to the public as a safe place for children in the school to take cover in the event of a nuclear war. When the bombs eventually fell in 2077, every designated family with a student attending the school, along with the teachers, made it to the Vault in time. Upon entering, the children were separated from their families and escorted to the atrium, while the adults were executed by security staff, under the guise they were receiving "orientation." This act of murder coincided with the purpose of the Vault, which was to enhance the gene pool of its selected residents to create stronger and more intelligent subjects. The surviving children were harshly tested mentally and physically - bordering on torture, and without regard for the survival of weaker individuals - as part of the experiment.
They were raised learning about the horrors of "Uptopland," a nickname for the newly made wasteland, and were told that they would be strong enough to venture out into the wastes and help the suffering people above upon graduation. If they were intelligent and physically well built, they were either "harvested" for their good genes when they turned eighteen, or those displaying good intelligence and obedience were recruited to the Vault's science team after graduation. The others who were deemed insufficient to the Vault's standards were executed upon reaching the age of eighteen after a ceremony "celebrating" their graduation. However, details found in the various terminals suggest that even those who "graduated" were killed after harvesting.
At some point, the Vault was opened and emptied. Some internal log entries suggest there was a rebellion among the junior test subjects, aided by a "graduate" scientist. This is backed by the way the bodies are placed in the Vault, indicating a quick and merciless breakout. Whatever the case, in 2287 there are no residents remaining, and the Vault is serving as a hidden Gunners stronghold within Malden.