Flint mine opens at Grimes Graves.

Around 2,500 BC, about the time many of the stones at Stonehenge were first raised, Neolithic miners used tools made from deer antlers to carve out a labyrinth of tunnels across 430 mine shafts, some up to 13 metres deep.

'The site was in use at the same time that Neolithic people were transforming their world on a massive scale and building impressive monuments across the British Isles, such as Stonehenge and Avebury.

This was the pursuit of the high-value jet-black flint which was formed millions of years ago by the debris of sea creatures on what was then an ocean bed.

The flint was sought after for its versatility and durability, as well as perhaps its spiritual value. The flint at Grime's Graves was of such good quality that it would have been used for fine, specialised tools, weapons and ceremonial objects. A giant hunk of flint, possibly from the area, has been found as far away as Avebury in Wiltshire.

Miners were believed to have been lured to Grime's Graves from far afield for its precious flint, and whole communities, including women, children, and even pet dogs, were involved in the mining process.

'It was not until 1868-70, when one of the pits was excavated, that this was even identified as a Neolithic flint mine.

To this day, most of the more than 400 pits remain untouched. Geophysical surveys suggest that the mines covered a much greater area. Standing above ground at Grime's Graves, first named Grim's Graves by the Anglo-Saxons (who believed it was the burial place of the god Woden/Grim).

Now thanks to a new structure over one of the mineshafts, known as Pit 1, visitors are able to easily descend 9 metres (30 ft) below ground into one of the flint mines dug more than 4,500 years ago. There visitors get to see the amazing engineering and geological knowledge the skills of the Neolithic workers had via projectors and objects found during the excavations.

Phoographs: English Heritage