The history of a Scottish castle which played a key role during the Wars of Independence may have to be rewritten.
Tibbers Castle in Dumfriesshire occupied an important site defending Nithsdale, one of the main routes into Scotland, during the 14th century.
A new geophysics survey has uncovered an enclosure, invisible to the naked eye, within the current castle.
It has led historians to conclude that the original fortification was much smaller than first thought.
The findings have given experts a more detailed understanding of the site.
Richard Oram, professor of medieval and environmental history at Stirling University, said: "The results of this research are very exiting and greatly help our understanding of this important site but of early castle building in Scotland."
The castle, near Thornhill, was initially thought to have consisted of a mound, known as a "motte", and two large "baileys", or fortified enclosures.
However the new research reveals that the original castle was built with just a single bailey, densely populated with timber buildings.
Historians believe that as tensions between Scotland and England led to war, the castle was rebuilt and expanded.
The survey was carried out by a team backed by funding from the Castle Studies Trust and Historic Environment Scotland.
Dr Piers Dixon, of Historic Environment Scotland, said: "Thanks to the funding received by the Castle Studies Trust we have been able to shed new light on this important castle of the Wars of Independence."
Tibbers Castle was taken by Robert the Bruce in 1306, before being quickly regained by the English.
This occupation finished in 1313, with the resurgence of Bruce's campaigns against the English.