In Roman mythology, the bough was a tree branch with golden leaves that enabled the Trojan hero Aeneas to travel through the underworld safely.
They discovered the remains while excavating religious sanctuary built in honour of the goddess Diana near an ancient volcanic lake in the Alban Hills, 20 miles south of Rome.
They believe the enclosure protected a huge Cypress or oak tree which was sacred to the Latins, a powerful tribe which ruled the region before the rise of the Roman Empire.
The tree was central to the myth of Aeneas, who was told by a spirit to pluck a branch bearing golden leaves to protect himself when he ventured into Hades to seek counsel from his dead father.
In a second, more historically credible legend, the Latins believed it symbolised the power of their priest-king.
Anyone who broke off a branch, even a fugitive slave, could then challenge the king in a fight to the death. If the king was killed in the battle, the challenger assumed his position as the tribe’s leader.