Project Ice Worm was a project at a secret USA base built under the Greenland icesheet to act as a research base for creating a hidden base for ICBMs.
Information can be found at:
http://defensetech.org/2012/04/06/inside-the-armys-secret-cold-war-ice-base/
http://en.wikipedia.org/wiki/Project_Iceworm
http://gombessa.tripod.com/scienceleadstheway
http://www.dtic.mil/dtic/tr/fulltext/u2/477706.pdf – a paper on the concept, design and history