An archaeologist monitoring digging in Whanganui's Wilson St found early plough marks, the ruts of a former road and postholes from a protective palisade.
The postholes are consistent with the location and nature of the Lower Stockade. It was built to fortify the block of the fledgling town that included the Commercial Hotel and settlers' houses when the town was threatened with attack in 1847, Annetta Sutton said.
Wilson St was being dug for months late last year, starting from the Whanganui River and running as far as Maria Pl. The excavation was across the site of earliest European settlement in Whanganui.
It was a known archaeological site where more pre-1900 remains were likely.
The dug corridor was needed for water, wastewater and drinking water pipes. It was 3m wide and deep in places and digging it needed authority from Heritage New Zealand Pouhere Taonga. Monitoring by an archaeologist is the kind of "rescue work" common when such development happens in an historic area.