A Neolithic flint mine has been made accessible to the public for the first time.

One of only 10 known flint mines in the United Kingdom, Grime's Graves, near Thetford, in Norfolk, is the only one to allow access.

The Neolithic site has more than 400 mines, some of them dating back 5,000 years, and Greenwell's Pit is now its second to be made accessible.

The pit was dug about 4,500 years ago using hand tools and was last mined about 4,000 years ago.

Visitors descend 40ft (12m) down a ladder to a series of tunnels, some stretching 197ft (60m), although access is limited to small guided tours.