The road widening and improvement scheme of the A1 in Northern Ireland, from Belfast to Newry, [shown in red on the Google map] revealed much about Northern Ireland’s history and development.
There’s a well-researched and fascinating paper on the archaeological work associated with the road works by Colin Dunlop.
it’s entitled – DOWN THE ROAD A Road to the Past Volume 1 The Archaeology of the A1 Road Schemes between Lisburn and Newry. It covers the environmental impact on the land in the ice-age, through the neolithic period, the bronze-age, medieval times, and right up to the present day.
Be warned, the paper is over 100 pages – though still interesting to dip into.