Foel Fenlli is the second-highest peak in the Clwydian Range at 511 metres, usually climbed from a car park at Bwlch Penbarra, and one of the most rewarding short walks within easy reach of Denbigh. The summit itself is ringed by the substantial remains of an Iron Age hillfort roughly 25 acres in size, built around 2,500 years ago, with strong ramparts surviving on every side and a single entrance at the western end.
Inside the fort's south-west quarter, archaeologists have identified around two dozen hut platforms, evidence of a real settled community living within the ramparts and drawing water from a spring near the centre of the enclosure — a reminder that these hillforts were homes as much as defensive strongholds. The site continued to attract activity long after the Iron Age: there is a possible Bronze Age burial mound within the fort, and in 1816 a hoard of some 1,500 Roman coins was discovered here, hinting at a long and layered history of use.
Foel Fenlli combines naturally with a walk over neighbouring Moel Famau, the pair forming one of the most popular hillfort-to-hillfort routes in the Clwydian Range, with Offa's Dyke Path running along the ridge connecting them both.
Foel Fenlli, at 511 metres, is crowned by one of the largest and best-preserved Iron Age hillforts in Wales, its multiple ramparts and ditches enclosing an area of roughly 10 hectares and offering a striking sense of the scale of prehistoric settlement in the Clwydian Range. The fort is thought to take its name from Benlli Gawr, a semi-legendary tyrant king of Welsh folklore associated with the hill.
The walk to the summit, often combined with neighbouring Moel Famau via the connecting ridge and the pass at Bwlch Penbarras, is a popular route for more experienced walkers, rewarding the climb with sweeping views over the Vale of Clwyd and a tangible sense of the area's deep prehistoric history.