The enduring wonder of dry stone walls
Dry stone walls are a feature of the British Countryside. There are estimated to be over 5,000 miles in the Yorkshire Dales alone, some dating back over 600 years to when they were built to repel wolves.
Built without cement or mortar, just how do they last so long?
Darren Lees is a dry stone waller from Holmfirth in West Yorkshire, who learned his trade from his father. Tom Lord is a historian and dry stone wall expert.
BBC News went to find out more.
Video Journalist: Dan Curtis
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