The location, in the old town cemetery, was used to guard an entrance next to what later became Cowane’s Hospital and dates back to around 1547.
The tower was used to protect Stirling during a period known as the Rough Wooing, when English forces under the Duke of Somerset attempted to force a marriage between Mary, Queen of Scots and England’s Edward VI.
It’s believed the towers were last in operation in 1746 against Bonnie Prince Charlie, during the Jacobite Uprising, before falling into a state of disrepair.
Dr Cook and his team have been researching the city walls for the last two years and he hopes further excavations will continue into 2024, when Stirling celebrates its 900th anniversary as a burgh.
Dr Cook said: “Stirling boasts arguably the best preserved defensive city wall in Scotland.
“It was long believed that only two of the bastions – the Thieves’ Pot at the Thistles Centre and Allan’s Primary School – had survived.
“However, I have since confirmed three more, with this one at the town cemetery the latest. It is built on levelled bedrock and has two gun loops in it and there’s even evidence of drilling associated with its eventual destruction.”
Stirling Council leader, Cllr Chris Kane, said: “It’s remarkable to think, as we prepare for the 900th anniversary of Stirling as a burgh, that our city is still giving up its historic and architectural secrets.
"This is another fabulous find that helps bring to life Stirling’s central role in the power and politics of Scotland.”