If the sculptor Anthony Gormley could be transported instantly into the countryside, the place he'd probably choose would be Hatterrall Ridge, a long spine of high ground that offers huge views and marks the ancient boundary between England and Wales.
"It's real moorland," he says. "You look down into Herefordshire to the east and you can imagine yourself as a Celt staring down on the lush pastures, working out which herd of cattle you're going to raid. It's very marked - the contrast between this wild, changeless moorland and the cultivated country."
The ridge forms part of Offa's Dyke path after it emerges from the woodlands of the Wye Valley and crosses the farmland near Monmouth.
"What's nice about Offa's Dyke is that it's a defined route," he says. "It's good for children because it's not easily lost, and it puts this ancient imprint on the landscape, which is wonderful - you're always looking for the ditch and the dyke and you see it in all sorts of ways.
"Sometimes it's on the skyline, sometimes it's lost in the woods, and sometimes it's not there at all, which makes it a bit like a treasure trail. I like that sort of intrigue, and the dyke gives the walk a very strong sense of history."
Gormley, famous for open-air works including the Angel of the North in Gateshead, the Iron Man in Birmingham city centre, and Quantum Cloud at the Dome, has been on several long-distance walks including two in the Himalayas. Usually he goes with other people.
"Walking for me is the best way of getting to know someone else and of getting to know yourself: you think about your life and it gives you a kind of perspective. But I don't think that's what I do it for - it's more for that lovely feeling when you get off the train or leave your car and you know that for days you've left it all behind.
"There's a fantastic sense of freedom and getting back into an elemental world where there's just you and the sky and the earth and the birds and the sheep, and you find a different place for yourself. I find that really healing - the body escapes, and the mind escapes as well, and with the rhythm of walking you can somehow think better - more progressively."
What was Offa's Dyke for?
It's virtually certain that the dyke was built by the king whose name it carries. Offa ruled the eighth-century Anglo-Saxon kingdom of Mercia and was keen to define his territory. Asser, writing King Alfred's biography in Wessex a century later, records that he built it "from sea to sea" - about 170 miles.
The purpose of the huge earthwork, in places 25ft high, is less definite. It may have been a military barrier, but there are no signs of forts or roads. According to archaeologist Cyril Fox, it was primarily a boundary agreed between hostile kingdoms.
There are no original records to settle the matter because Mercia was almost completely destroyed by the Vikings in the 9th century.
"It was a powerful message to Offa's enemies, and to other kings including Charlemagne, who was building up his empire in France at that time," says Ian Bapty, Offa's Dyke archaeological management officer.
"Whatever the original reason, it has had an enormous influence on patterns of settlement and cultural identity, a line in the landscape behind which people have thought of themselves as Welsh rather than English.
"It's the only place in Europe where an earthwork gives you such a strong sense of cultural geography."
