THE extent of Scotland's military defences during the First World War have been unearthed by a major archaeological audit.
The study was commissioned by Historic Scotland and the Royal Commission on the Ancient and Historical Monuments of Scotland (RCAHMS).
It found an enormous amount of information regarding the conflict's built heritage.
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Top-secret anti-invasion placements, scattered around Edinburgh and parts of East Lothian, were among the most notable finds made during the investigation.
In total, around 900 buildings and other sites have been added or updated to Scottish records.
Dr Gordon Barclay, the author of the study, said: "The audit has more than tripled the number of places known to be associated with Scotland's contribution to the First World War, and has revealed an extraordinary variety of structures, reflecting Scotland's importance to the war effort.
"The audit is only the first step, and other places no doubt remain to be identified, and the wartime role of many other places will certainly come to light during the centenary of the war."
Scotland's amended record includes 64 air stations - 30 of which were previously unknown.
There were also 39 prisoner of war camps in Scotland, with the main site being situated at Stobs, near Hawick.
A total 11 naval dockyards or naval bases have been detected, while at least 15 barracks were found.
Allan Kilpatrick, of RCAHMS, added: "Scotland was on the front line during World War One.
"Large parts of the landscape were transformed by structures designed to repel any invasion or attack, and it is remarkable just how many WWI remains can be still be seen today."