A unique mill and mill-race, which could be as old as the eighth century, have been excavated at a building site in Chapelizod, Dublin.
The archaeological site director, Ms Claire Walsh described the find as "superb": the "most complete example of a mill of its type to be uncovered in Ireland".
To the ordinary citizen the site looks like a pile of stones with a water channel running through it, but to archaeologists it is an "industrial complex" of the pre-Norman period. It is the "undercroft" or basement area of the mill with some "very fine masonry".
Ms Walsh described it as a "first-class find" and rated it as one of the top three excavations she had ever worked on. The mill and mill-race - the channel in which water runs to drive the mill - were uncovered in March during site clearance by Zoe Developments, which is building an apartment complex in Chapelizod village.
Ms Ruth Johnson, Dublin City's archaeologist, said the company had observed "best practice" in the preservation of the site, in accordance with Dublin City Council and Dúchas, the Heritage Service. Construction work ceased and a full excavation began, which is expected to continue for another fortnight.
Some 20 archaeologists are currently working on the site, which is on one side of an 18th- century man-made island with the river Liffey on the other. Ms Walsh said the early residents had dug an artificial channel further up from the river and diverted it to the mill.
The structure will be preserved intact but will be inaccessible under the floor of a basement car-park for the complex. Ms Walsh said that water was the problem. "We have several pumps constantly on the channel and it is still infilling with water."
Archaeologists are happy to have two major achievements - "to excavate and get a full record of the site and to preserve it in full in situ".
A few other artefacts were found on the site, including part of a "classic Hiberno-Norse, late-9th or early-10th century" polished stone bracelet and the shaft of a ring pin for a brooch. Workers also uncovered a neolithic modified polished stone axehead, some 5,000 years old.
Pottery, evidence of later settlements, was also found, including a dundry stone mortar or bowl, carved out of bath stone that was imported in the 13th century and used mainly for decorative work.
When the excavation is complete, all the artefacts and a complete report, including photography, will be handed over to the National Museum.
