Bertha was a Roman fortress north of the site of modern Perth, in Scotland at the confluence of the rivers Almond and Tay. It is half a mile east of the modern farm of "Berthapark". One source contradicts the view that Perth was a corruption of the fort's name. According to this source, the name "Bertha" was originally used by medieval Scots historians, such as John of Fordun and Walter Bower, who did not know the original name for the site and who adapted a version of "Perth" - Berth". The Romans probably called the site "Tamia", after a native name for the River Tay. In early medieval times the abandoned site was still used for ceremonial purposes by Pictish and Gaelic kings, when it was called "Rathinveramon".