The following is based on Van Buren and has not been confirmed by canon sources.
Moletown is a small town outside of the Tibbets Facility where a crazy survivalist had trapped all the buildings and dug out a series of tunnels beneath the town to try and wipe out anyone or anything that tried to crawl in there.
Moletown was to appear in the canceled Fallout 3 project by Black Isle Studios codenamed Van Buren. It was, however, eventually cut from the game, as it does not appear in any of the design documents. However it has some features quite similar to Bombay Jack canyon in Denver and Bill Hatch location described at Burrows design document (the wood cutter's wife quest).