Vault 76

Vault 76 is one of the Vault-Tec vaults shown on the computer in the Citadel. The Vault-Tec Terminal in the Citadel lists Vault 76 as a "control" vault, with 500 occupants. The vault was designed to open after 20 years. It was among the seventeen total control vaults, meaning it functioned precisely according to occupants' expectations.

Appearances
Despite being mentioned in Fallout 3, Vault 76 does not appear in the game. The game used to feature the Vault, but no purpose could be thought of for it so the developers scrapped it.