Bedrule Castle in Bedrule, near Hawick in the Scottish Borders, was destroyed by Henry VIII forces in September 1545 during the Rough Wooing invasion.
The castle was one of the 12 Towers of the Rule Valley destroyed by the English following their defeat at the Battle of Ancrum near Jedburgh in February that year.
Originally built in the 13th century by the powerful Comyn family, it is believed Bedrule Castle sat behind an oval-shaped curtain wall with an collection of houses and enclosures within.
Kieran Manchip, project officer at Archaeology Scotland, said the possible remains of a spiral staircase and pottery were found during the first phase of the excavation last month, with hopes to return next spring.
Mr Manchip said: "Bedrule is one of the 12 Towers of Rule, which seemed to be destroyed over just a couple of days by the English.
“The site is not very well known and not very well understood and this is the first time it has been excavated.
"All you can see at the site is a series of humps and bumps and you don’t look at it and think a castle once stood there.
"The site is not scheduled at the moment, but I expect that will soon change.”
The Comyns, who became key adversaries of Robert The Bruce, were one of the most dominant families in Scotland, with King Edward 1st of England staying at Bedrule in 1298, according to accounts.
After the English defeat at Ancrum Moor, the Earl of Hertford was ordered north with 12,000 men and 4,000 horses, with instructions to “burn and destroy the country about, sparing neither castle, town, pele nor village”.
Letters to Henry VIII from the Earl of Hertford list names of the places that were obliterated from the landscape, with a dozen places burnt to the ground. Bedrule was among them.
Bedrule Castle was awarded to Sir James Douglas in 1306 after its owner, Sir John Comyn, was killed by Bruce at Greyfriars, Dumfries.
The castle then passed to the Turnbulls, with James IV said to have hung several members of the family on a visit to the castle, according to an account by the Scottish Castles Association.
By 1591, Bedrule Castle had fallen into a ruined state.
According to accounts, the barony associated with Bedrule Castle was bought by a Wallace Rutherford Turnbull from the United States in 2015, who has also taken on the role of Clan Chief.
Mr Manchip said wider work was ongoing to identify and strengthen information on the 12 Towers of Rule Valley as part of work to develop plans for a Scottish Borders National Park. A number of abandoned settlements will also be investigated.
A site near Bonchester Bridge would also be excavated as part of the research into the Twelve Towers of Rule.