[If the text below uses any of the terms ‘hill-letter’, ‘river-letter’, ‘old-style name’, ‘transitional name’ and ‘inversion-type name’ a reader who is not familiar with those terms may wish to refer briefly to ‘The Celtic names of hillforts’, where an explanation of those terms is given].

The Celtic names of hillforts

Castle Law

Location: south-southeast of Forgandenny, Perth and Kinross

OS map reference:  NO 100 155                                                       

Celtic name: probably  Cermium

Source:  Ravenna Cosmography (223) - Cermium

This hillfort stands at the top of a very steep slope forming part of the northern edge of the Ochil Hills. To the southwest the land continues rising to the summit of Culteuchar Hill, at 313 metres above sea level.

The name is straightforward. The hill-letter m is qualified by the earlier old-style element Cer meaning ‘steep hill’, presumably a reference to the steep hill on the north side of the fort. The name indicates that those who used the hill-letter r occupied this site before those who used the hill-letter m, which is contrary to the normal chronological order of these hill-letters in Britain.

It is not clear whether the name as it appears in Ravenna refers to the hillfort itself, to a possible Roman post set up inside the hillfort after the occupants had been evicted, or to a Roman post down in Strathearn and to which the name of the hillfort was simply transferred. The third possibility seems the most likely, such a Roman post probably being one of the forts said by Tacitus to have been built by Agricola at the end of his first campaigning season in what is now Scotland. The writer’s reasons for associating the name Cermium with this area are given in Chapter 16 (Roman place-names in Scotland) of the Home menu.

Note that we cannot take it as certain that the Castle Law Forgandenny hillfort was called Cermium since there is another fort a little further north on the Law of Dumbuils. If the archaeologists could prove that the Dumbuils fort was not occupied at the date of the Roman invasion then we could be quite sure that the Castle Law hillfort was indeed Cermium.  Note that at the date of the Roman invasion the hill-fort was in the hands of the Damnoni, who used the hill-letter m (see  'Ptolemy's Celtic tribes in Britain').