Ireland's maps: Retracing how they made world history
Two centuries ago Ireland was the setting for the world's first large-scale mapping of an entire country.
A group of academics are retracing the steps of the surveyors who completed the Ordnance Survey map in 1841 without modern technology.
BBC News NI’s cameras joined them as they scaled Binevenagh Mountain in County Londonderry, which was a focal point of the survey.
The group are trying to understand more about how surveyors used equipment such as chains to measure distances over treacherous mountain terrain.
Mapping Monuments is a Queen's University Belfast project with the Causeway Coast and Glens Heritage Trust.
It received funding from the National Lottery Heritage Fund and is part of a series of events leading up the 200th anniversary of the ordinance survey.
Video journalist: Niall McCracken