The ancient Greeks had an amazing way and ease in discovering veins of ore and excavating galleries that followed the various directions the veins could lead them. Although all the antique mines had already been exhausted in antiquity, the “hollow mountains” have remained. They cannot however be identified or located, since no exterior characteristic or indication has survived. The reason is that the ancient mines did not transport outside the mine the rubble and waste produced from the excavation of a new gallery, but filled with it already exhausted one. Relevant reference that confirms the application of this method is cited in Herodotus, who mentions that the mountain opposite to the island of Samothrace was a “hollow mountain” excavated in search for ore.