In Norfolk, there is a field with 400 pits; what is this field, which resembles the moon's surface?

Inside Neolithic flint mine Grime's Graves, near Thetford (Image: Newsquest)

Grime's Graves, originally known as Grim's Graves, is a Neolithic flint mine and Site of Special Scientific Interest that serves as a refuge for endangered plant species.

One of the pits was discovered to be a network of flint mines that had been dug more than 5,000 years earlier when it was unearthed in 1870.

English Heritage looks after a grassy environment with more than 400 shafts, pits, quarries, and spoil dumps on the property, which also houses Britain's sole accessible prehistoric flint mine.

It was discovered in 2011 during a dig that the region was larger than first believed. While this does not necessarily mean there are new sites to find, it may point to a greater area of archaeological importance.

The Stone Age archaeological site is currently closed for conservation work, however it is frequently open to visitors when they can descend nine meters by ladder to observe black flint.

Up to nine persons could have participated in the pit digging at once during the seasonal Neolithic villages.

They would fill the mineshaft back up with the materials they were taking out to make the next pit once they had completed digging the first one.

Canon William Greenwell conducted the first excavations at the location between 1868 and 1870, confirming that it was a flint mine. Greenwell's Pit was once more excavated in 1971–1972 and by the British Museum in 1974–1976; it has since been abandoned.

The hole contained a greenstone axe from Cornwall, antler picks, and a bird's skull.