Forgotten for centuries, Kilmartin Glen in Argyll is one of Britain's most important archaeological landscapes – but most people have never heard of it. On the road north-west from Glasgow through the hills of Argyll, civilisation peels away and the landscape becomes emptier of life and stories – but only to the untrained eye. As the road clears Loch Fyne, curving north out of the village of Lochgilphead, the great expanse of Kilmartin Glen comes into view.

This was once the Scotland seen by the 6th- and 7th-Century kings of the ancient Gaelic kingdom Dál Riata , and the raised bogland greets the visitor with rumpled hills, fields settled by Blackface sheep and forests planted with deeply-rooted oak. But look closer – much closer still, as the road weaves north to harbour town Oban – and it quickly becomes clear that Kilmartin Glen is a place where history lurks in great abundance. For this is the setting of a prehistoric collection of henge monuments, burial cairns, standing stones, cist chambers, stone circles and the densest concentration of rock art sites anywhere in Britain , with more than 800 ancient relics at the last count.

This multitude was built before the Romans and Greeks came along, before the first pyramids were built some 4,700 years ago and before Stonehenge, Britain's other great prehistoric monument. Interpretations of Kilmartin Glen by various archaeologists and antiquarians all agree it is one of Britain's greatest treasures. Yet the strangest .