Running down the hillside to an entrance set in the northwest corner of the medieval vaccary (cattle ranch) of Hen Ddinbych (NPRN 303472) is a 125m long hollow way 5.4m wide and up to 1m deep.
This hollow way was surveyed as part of the 2009 RCAHMW survey of the Hen Ddinbych landscape (NPRN 411894)
