Archaeologists and volunteers spent more than two years constructing a 10m tall replica of an Iron Age stone-built tower - only to demolish it.
Previous projects at Spital recreated a Neolithic chambered cairn
The project, run in a quarry at Spital, near Thurso, Caithness, was part of research into brochs.
There are estimated to be 200 of them lying in ruins in the region.
Knocking down the reconstructed tower is helping archaeologists to better differentiate tumbledown brochs from the remains of other buildings.
It is one of a series of projects being led by Caithness Archaeology Trust.
Others include investigations of a shipwreck which is believed to be that of the V81, a World War I German destroyer.
Dr Andrew Heald, curator in archaeology at the National Museums in Edinburgh, has been examining the remains of three brochs near Keiss along with John Henderson of Nottingham University, John Barber of AOC Archaeology and the Caithness trust.
He said a copper mining boss, Sir Francis Tress Barry, who had lived at Keiss Castle, excavated 15 brochs between 1890 and 1904.
"Everyone has been ignoring Caithness for the last 50 years mainly because the Tress Barry excavations, which were of his time but quite coarse, were thought to have jeopardised the research," said Dr Heald.
The archaeology team and local volunteers were now "playing a game of poker", he said, digging deeper in the hope of find artefacts missed by Sir Francis.
Dr Heald said: "We have found a hearth which in academic terms is important to dating the original structure."
The earliest brochs were thought to date back to 500BC.
Muddying the waters in Caithness has been the towers' reuse by the Picts, Vikings and people during the medieval age.
Stones have also been quarried or robbed for other uses and many of the buildings, which once provided accommodation, are nothing but rubble.
To aid their work in identifying a ruined broch, archaeologists and volunteers constructed their own one.
Dr Heald said: "It was half the size of a real broch - 10-15m in height - and built over two years.
"Local children jokingly made Save Our Broch placards."
The way that the mock broch collapsed revealed the shape of a ruined ancient building.
Work at site of three brochs near Keiss was expected to be wrapped up for this year by the end of the week.