Today the site comprises the remains of the hill fort and two Roman military camps, one on each side of the hilltop.
Archaeologists think the camps were used by the Roman forces to stage an "all-out attack" on the defenders, as a punishment for their resistance to Roman rule.
This image shows Burnswark Hill from the north, with one of the Roman camps visible on the slopes. [Read the full story on the sling bullets]
The largest are about 1.2 inches (3 centimeters) long and weigh about 1 ounce (30 grams).But about 20 percent of the Roman sling bullets found at Burnswark Hill are smaller and have been drilled with a 0.2 inch (5mm) hole, including the two bullets at the bottom of this image.
John Reid, an archaeologist with the Trimontium Trust who has studied the unusual sling bullets, believes they were designed to make a noise in flight to keep enemy heads down. [Read the full story on the sling bullets]
Excavating in Scotland
As well as making a detailed geophysical survey of the site, the researchers have used sensitive metal detectors to identify buried deposits of particular metals — such as the lead used in Roman sling bullets — without disturbing the ground. [Read the full story on the sling bullets]
The researchers say the large quantities of Roman ammunition found at Burnswark Hill indicates that they wanted to inflict a crushing victory over the defenders that would send a message to other rebellious tribespeople. [Read the full story on the sling bullets]
It used torsion springs made from twisted rope to shoot iron-tipped bolts at ranges up to 400 yards (400 meters), and it could fire up to four bolts a minute. Early Roman legions were equipped with a contingent of 60 Scorpios that could fire a combined 240 bolts per minute at the enemy.
In this image, a reenactor named Quintus shows pieces of Roman pottery to visitors at an Open Day at the Burnswark Hill site.
Images of military slingers are found in several ancient carvings, including this wall fragment on display at the British Museum from the Neo-Assyrian city of Nineveh, located in what is now Iraq. Dated from the beginning of the seventh century B.C., it shows Assyrian slingers in action at a siege of the Israelite city of Lachish in 710 B.C.
Later Roman sling bullets were often inscribed with slogans that invoked the names of commanding generals, including "For Pompey!" and "Victory for Caesar!"