Babylon

Babylon was an ancient city, the capital of Babylonia.

Honest Hearts

 * Joshua Graham mentions Babylon twice in a quote from the bible.
 * There is an achievement called O Daughter of Babylon.

Wild Appalachia

 * It's mentioned in the Pioneer Scout archaeologist exam and gardener exam

Appearances
Babylon is mentioned in the Fallout: New Vegas add-on Honest Hearts and the Fallout 76 add-on Wild Appalachia.