'It's magical' Neolithic mines in Norfolk reopen to visitors

Nine metres below the grass level of an undulating Norfolk field, at the bottom of a very deep hole, Jennifer Wexler is talking about what makes this subterranean space particularly special.

- Esther Addley

"I've spent a lot of time crawling around [down here], and you can go into certain spaces where you see someone's tool and think: someone just put that down 4,500 years ago, and it's still here," she says.

"You can literally see their marks on the wall, the tools they used, it's a really unique experience.

And that's why for me, every time I go down, it's completely magical." Wexler is the senior properties historian for Grime's Graves, a remarkable prehistoric site near Thetford where, for several centuries in the late neolithic period, people dug huge mineshafts deep into the Norfolk chalk, scratching with nothing more than deer antlers to reach seams of precious jet black flint.

More than 430 pits have been found, some up to 14 metres deep and 12 metres in diameter, though there may be as many as 600.

Almost uniquely among Neolithic sites in England, visitors have long been able to climb down a rickety ladder to the base of one of the mineshafts to explore the authentic late stone age site.