Cradles are cryostorage facilities built to service the ELEUTHIA function of Project Zero Dawn. These numbered underground bunkers were constructed around the world to eventually repopulate the Earth with humans once the biosphere was returned to a habitable state. Cradles were often built inside mountains.
Dr. Sobeck's hologram introduction to GAIA includes a map of Cradle locations. There appears to have been at least one located in the present-day countries of France, Russia, India, Afghanistan, and Greenland.
ELEUTHIA-1 was constructed somewhere near the Xinjiang province in northwest China.