Archaeologists have discovered the buried remains of a Roman fortlet that once stood next to the Antonine Wall and was thought to be lost to the mists of time.
Historic Environment Scotland (HES) experts made the discovery during a geophysical survey in a field near Carleith Primary School in West Dunbartonshire.
Previous excavations to find the fortlet were unsuccessful, but new technology allowed the HES archaeological survey team to find the buried remains.
The survey team used gradiometry, a geophysical surveying technique, to look under the soil without the need for excavation.
This technique was able to identify the stone base of the fortlet, which remains buried underground. On top of this base, turf would have been laid to build a rampart about two metres high.
HES said that the newly-discovered fortlet would have been part of several such structures along the Antonine Wall.
It would have been occupied by 10 to 12 Roman soldiers who were stationed at a larger fort nearby, likely to be at Duntocher, and manned the fort for a week at a time before being replaced by another detachment.
Riona McMorrow, deputy head of World Heritage at HES, said: “It is great to see how our knowledge of history is growing as new methods give us fresh insights in the past.
“Archaeology is often partly detective work, and the discovery at Carleith is a nice example of how an observation made 300 years ago and new technology can come together to add to our understanding.”
The announcement of the discovery comes on World Heritage Day, the international celebration of cultural heritage.
The Antonine Wall is one of Scotland’s six Unesco World Heritage Sites.
This discovery has led to HES reviewing the site’s designation to ensure the fortlet is recognised and protected as part of the Antonine Wall.
While up to 41 fortlets may have lined the wall when it was built, only nine have previously been found.
HES said that the geophysical survey will help to better understand and protect the Antonine Wall.