X-66 Hexcrete Archipelago

 is a location in the Big Empty in the Fallout: New Vegas add-on Old World Blues. It is directly north of the Z-38 Lightwave Dynamics Research station, south east of the X-13 testing facility and west of Z-43 Innovative Toxins plant.

Layout
It is made up of many large hexagonal prisms sticking upright from the ground, ranging in height from shorter than a player to several stories tall.There is also a pool of radioactive liquid which had 1 rads per second. Two packs of nightstalkers spawn to the south and east, in range to attack any player. Also, its proximity to the X-13 research facility means that any Robo-scorpions guarding it will attack you if you venture north from this location.

Appearances
This location appears only in the Fallout: New Vegas add-on Old World Blues.