A clapper bridge. One of the original bridges on the moors.

This Clapper Bridge can be found at Postbridge, on Dartmoor. Its slabs are over 4 metres (13 ft) long, 2 metres (6 ft 7 in) wide and weigh over 8 metric tons (7.9 long tons; 8.8 short tons) each, making the bridge passable to a small cart. It was first recorded in 1380 and was built to facilitate the transportation of Dartmoor tin by pack horses to the town of Tavistock