Vault 8 of western Nevada was an ideal control vault supplied with a Garden of Eden Creation Kit, housed only about 100 dwellers, and opened as intended after the nuclear fallout faded away.
The vault itself became one of the best public medical centers of the wasteland and when it opened, its residents left with a GECK, immediately turning the arid land into a fertile area and used the Vault's reactor as a primary power supply for the region. However, the citizens of this high tech community are typically racist xenophobic elitists, treating the outsiders poorly and generally uncaring of the outside world. The only outsiders who receive benefits are the servants to the community(slaves).
Eventually, the NCR launched an initiative to force the Vault City into their growing empire, but it is unknown whether that initiative has succeeded.