The curves and contours of the landscape reveal a tantalising glimpse of Wales’ prehistoric past.
It’s where our ancestors lived, worked and died nearly three thousand years ago.
In the latest episode of Wonders of the Border, Sean Fletcher explores the Iron Age hillfort of Penycloddiau, an imposing landmark in the Clwydian Range that rises 1,500 feet above the Vale of Clwyd.
The ITV series follows Sean as he travels along the Wales-England border, following the Offa’s Dyke Path.
The Offa’s Dyke Path walking trail leads directly to the hill’s summit, and many visitors will be unaware of what lies beneath their feet - but the grassy mounds that form a perimeter around Penycloddiau provide a clue.
Inside those mounds are a series of solid, dry stone walls, two to three metres wide. They form the outer edge of the hillfort and the scale of the construction is astonishing.
For archaeologist Fiona Gayle, Penycloddiau reveals a highly sophisticated building project.
"It’s phenomenal. It’s one of the largest hillforts in Wales and it’s enormous," she explained.
"It stretches two miles, all the way round. These days, the idea of building a two mile long, three metre wide dry stone wall around an entire hill would be a huge civil engineering project. It’s a massive undertaking. But our ancestors managed it.
"It’s easy to think that the people in the past were just not very clever, but Penycloddiau proves that’s not the case at all."
Very little remains of the hillfort above ground, but archaeological research and excavations paint a picture of what life would have been like in north Wales in around 500 BC.
The 50 acre enclosure would have contained around 90 timber roundhouses, probably with thatched roofs. The community would have included both adults and children and was largely self-sufficient.
Animals provided food, ponds supplied the inhabitants with water. The land was farmed, goods were traded, rituals were celebrated.
This was a community in the clouds.
Although the scale of this fortified settlement is breathtaking, remarkably it’s just one of six Iron Age hillforts along the Clwydian Range, marking this corner of Wales as one of the most intriguing and historically significant landscapes in Britain.
You can see more on this story in Wonders of the Border at 7:30pm on Thursday 27th May on ITV Cymru Wales.
You can then stream online at itv.com/walesprogrammes.