Vault 74

Vault 74 is one of the Vault-Tec vaults located in the Capital Wasteland. Not much is know about its fate except that it was overrun by raiders. It is small, consisting of just an atrium, a clinic, and an overseer's office.

Related quests
The Vault comes with a simple quest called "Exploring Vault 74". You start the quest by simply entering the vault and you complete the quest by taking the Vault 74 Overseer's log.

Appearances
Vault 74 is a Vault that the Bethesda Softworks developers made for the official G.E.C.K. tutorials and it does not appear nor is mentioned anywhere else. Given that, the location is likely non-canon.