Historic Scotland architects studied plans drawn up in the 1700s to figure out the best way to defend one of its properties from the sea.
Original architects' sketch of wall and sea defences
Major repairs are planned for the south walls of Fort George - an 18th Century artillery fort on the Moray Firth.
The original architects' sketches revealed a barrier against the sea was created using shingle.
Borrowing from this idea, rocks will be used to shield the wall from waves while the repairs are carried out.
James MacPherson, district architect at Historic Scotland, said the south walls took the full force of the sea.
He said: "We were considering some highly technical solutions, but I wondered how they had tackled the problem in the 18th Century.
"Looking through the original plans, I found sketches showing that shingle from the beach had been built up into a huge protective barrier in front of the walls.
"This made a real difference to our thinking as we realised we could create a modern equivalent which would be simple but very effective."
The new barrier will be 3m (9ft) high and 210m (688ft) long and consist of 2,000 tonnes of rocks.