The team from the Strathearn Environs and Royal Forteviot (Serf) project say the Iron Age broch they have found near the village of Dunning in Perthshire is the first of its kind to be discovered in the Lowlands for a century and is exquisitely preserved.
The broch, a massive stone wall more than 2ft high and 5ft thick, lies at the top of a hill giving a 360-degree view of the countryside. Experts say it was the kind of dwelling that would have been the preferred residence of the elite.
It is believed the broch was destroyed by fire and the Picts later built a fortress on top of the site for one of their warlords.
Stephen Driscoll, professor of historical archaeology at the University of Glasgow and director of the Serf project, said: “There can be no doubt that we have located one of the major centres of Pictish power from the first and second centuries.
“The scale of the architecture is colossal and the tower-like structure would have visually dominated its surroundings.
“It’s not unreasonable to see this as a seat of a Celtic chieftain, who collected a wide range of luxury objects from the Roman world, perhaps through trading with the Romans or possibly even serving in the Roman army.”
The Serf team, from the universities of Glasgow, Aberdeen and Chester, have been carrying out archaeological digs in Dunning and Forgandenny since 2006, when the project began to look at the area – a major royal centre in AD 858 and also the site of early prehistoric ritual monuments.
Inside the broch, the team discovered an array of Roman artefacts, including a glass vessel, a lead bowl, bangles made of glass and bronze and fragments of iron.
Mr Driscoll said: “The artefacts are of particular interest as they date to the time of the first contact with the Roman world and offer numerous clues to how the Picts might have begun their interactions with the Roman Empire.
“This is the best example of an Iron Age Roman site being reoccupied by the Picts.
“We have long suspected that this happened, but now we can examine the Picts’ relationships with the Romans in much more detail.
“The majority of the known Lowland brochs were excavated poorly by antiquarians or were not as well preserved as the items we’ve uncovered.
“The discovery of these items is particularly valuable as it will allow this high-quality material to be examined in a disciplined manner in future years and play a role in developing our understanding of this area of Scottish history.”
Culture Secretary Fiona Hyslop said: “The wealth of information coming from this excavation is incredible, with potentially far-reaching implications for how we view our history. “