The search under the surface of the planet for particular types of stone and metal started in prehistory. Flint, which was used for weapons and tools, was one of the first stones to be mined. Seams of the stone on the surface would gradually be mined and hollowed out, and Paleolithic man soon learned to follow the seams further into the surrounding rocks. By the Neolithic period (from about 12,000 years ago onwards), there were significant numbers of mines and tunnels around the world. The oldest we have found is in the Lion Cave in Swaziland, which has been dated to about 43,000 years ago. Paleolithic humans mined a mineral called hematite here, which can be made into the red pigment called ochre. From a similar period there are flint mines in Hungary, suggesting that Neanderthals may also have been able to dig tunnels for their tools.
The ability to dig tunnels down into the rock led to a significant improvement in humankind’s tunnelling ability by the time of the ancient Egyptian and Babylonian cultures. Large building projects in Egypt in the early third millennium BC relied on the mining and quarrying of malachite, copper and turquoise, from sites scattered around North Africa and the Middle East. The gold mines of Nubia were amongst the most extensive of ancient times. By 2180–2160 BC, the Babylonians had the technology to dig a tunnel of 3,000 feet (914 metres) in length that passed under the Euphrates river.
One of the most fascinating archaeological finds of recent times is the existence of hundreds of tunnels in the rock under Neolithic settlements in most parts of Europe. Hundreds of these have survived to the present day: archaeologists have recently estimated that there must have been thousands of them across Europe, from northern Scotland to the shores of the Mediterranean. These tunnels are large enough for a person to crawl through, with occasional chambers and rooms. It is unclear whether they were used for travelling safely from place to place or as a refuge, but the effort that went into digging them out of the rock suggests they must have been highly important.