Castercliff Hillfort was built in a defensive and strategic position, high on a ridge spur. It was situated at the meeting of two important Iron Age routes. The first runs through the Aire Gap and would take the traveller north to the area dominated by Ingleborough Fort.  The second route runs through the Cliviger Valley to the Huddersfield area, which was controlled by a large hillfort at Almondbury.

Castercliff Hillfort, Nelson. A rampart and ditch can clearly be seen in this picture. Part of the panoramic view can be seen in the background.

Historical sources suggesting who may have been responsible for building Castercliff are scant but there are two contenders: firstly, the Brigantes (or ‘hill people’) who were a large tribe that ruled the Pennine area; and secondly, the Setantii, a sub-tribe of the Brigantes, who had the coastal territory of Lancashire from the River Mersey in the south to the River Lune in the north.

Construction of the Fort

The oval shaped site covers four and a half acres in total. The fort defences consisted of three ramparts which differed in their types of construction, and may well not have been built at the same time. The site dates from around 500 BC.

The inner rampart is of the construction type classed as ‘stone with timber lacing’. It consisted of a double row of timber posts. Each post was two metres apart from its neighbour. Between the posts were horizontal wooden beams to strengthen the structure. The spaces between the posts and beams were filled in with earth and loose stones. The outward looking side was revetted (or faced) with stone. The method of construction seems to be similar to a rampart at nearby Portfield Fort, in Whalley.  The inner rampart did not have a defensive ditch dug in front of it, but many forts in Lancashire and Cheshire lack this feature too.

The outer rampart was narrower than the inner one, and of the type classed as ‘timber frame box’ . This was made by driving timber posts into the ground and then constructing a box around them to hold in a soil-filled interior. The core of the infill was made of clay, and the outward-looking side was faced with timber. In front of the outer rampart was a ditch that was cut into the underlying rock. With a depth of 1.5 metres, in front of a rampart 1.5 metres high, this would have been a formidable obstacle. There is also evidence of a palisade (wooden fence) in front of the ditch to give further protection to the site.

Satellite photograph of Castercliff. An oval shaped fort, parts of the ramparts can be seen on close inspection. The circular features are Victorian bell pits. Photograph courtesy of Google Maps. 

Destruction of the Fort

It would appear that the fort was abandoned after it was attacked and subjected to a fierce fire. The evidence for this is that many of the rampart stones appear ‘vitrified’, a form taken when subjected to an intense heat. One of the ramparts also appears to have been unfinished, which could again hint at a sudden disruption to the settlement. It’s not thought that vitrification occurs during an attack, as any fires started then could not burn hot enough to cause the stone to vitrify. This means the burning was deliberately done after the fort was captured. Timber would be stacked against the ramparts and set ablaze to give a controlled, intense burn. The vitrifying and shattering of stone, together with the burning of the wooden timbers, would significantly impact the defensive capacity of a fort. 

It’s not clear who did this, or when. It’s possible to speculate that it was the Romans, but other forts in Lancashire continued to be occupied in Roman Britain, for example Castlesteads near Bury. Alternatively, it could have been done by another Iron Age tribal group. Interestingly, most vitrified forts occur in Scotland, which might suggest knowledge from that region being exercised here.

Vitrified stone from the intense burning of the fort can still be seen.

Antiquarian Interest

Although the area must have been a well-known landscape feature for many years, records show that in Victorian times investigators began to become interested in the history of it. In the 1800s, Thomas Turner Wilkinson, a historian from Burnley, wrote  “we are informed that many hundreds of tons of stones have been carried away from the walls within the last 30 or 40 years, all of which appear to have been subjected to intense heat. Large quantities still remain half buried in the soil, many completely vitrified and others presenting a singularly mottled appearance from only being half burnt through. The burnt sandstone and lime form excellent manure, and at the time of our visit a luxuriant crop of corn and cabbages had just been gathered from the ditches of the camp”.

Another local historian, W. Thompson Watkin, wrongly thought the site was Roman. He described it as a parallelogram, with rounded corners. He observed what he thought was a double vallum (bank) and fosse (ditch) surrounding it. He commented on the large quantities of stones lying about, most half-buried in soil. He wrongly thought that the stones had come from buildings, but noted their vitrified state from being burnt. He backed up his Roman claim by stating that Roman coins were found at foot of the hill. Interestingly, three more Roman coins from the 3rd Century AD were discovered in 2012 at nearby Hill End Farm.

More recent records show that the fort had been partially damaged by open cast mineral extraction. Bell pits were dug to excavate coal. These circular structures can still be seen on the surface today.

Part of a circular bell pit used to dig for coal

Archaeological Excavation

In the second half of the twentieth century,  excavation began in earnest to uncover the archaeology of the site. The Reverend J.A. Plumber carried out digs in 1958 and 1960. He cut through the north-west corner of the site to inspect the defences. Here he discovered the-flat bottomed ditch, cut into the rock. He also claimed to have found evidence for iron smelting furnaces in a disturbed area behind one of the ramparts. 

During the years 1970-2, David Coombs led a dig as training for archaeology students from the University of Manchester. The excavation uncovered the differing construction techniques to build the ramparts, and the extent to which they had been damaged by fire. Wood from the inner rampart was dated to 510 BC (plus or minus 70 years). This fits in well with the general dating of this type of ‘stone with timber lacing’ ramparts seen elsewhere in the country. The outer rampart’s clay layer was found to be extensively burnt and covered in a layer of charcoal. Some of the burnt timbers were analysed and discovered to be oak. 

A public footpath takes the visitor onto the site of the hillfort. The ramparts and ditch can clearly be seen on the climb up to the top.

Near the centre of the inner enclosure were post holes of a structure which was possibly a grain store. However, the tell-tale post holes of Iron Age round house structures remained elusive. More investigation will be necessary to work out where exactly the people were living within the fort.

Flint tools found at the site show that it was known to prehistoric people perhaps as far back as 3000 BC. It would have been a good vantage point from which to survey animals to hunt. The finds of Roman coins nearby suggest some ongoing connection with that era too.

Site visited by A. and S. Bowden 2020


There is a public footpath onto Castercliff Hillfort. Park in the layby on Back Lane.


Prehistoric Lancashire, David Barrowclough (2008) The History Press

Hillforts, Homesteads and Habitats in the East Lancashire Pennines, John A Clayton (2018) Barrowford Press

Man and the Changing Landscape, Bernard Barnes (1982) Merseyside Council/Merseyside County Museum

Historic Walks Around the Pendle Way, John Dixon and Bob Mann (1990), Aussteiger Publications

The Archaeology of Lancashire: Present State and Future Priorities, Richard Newman (Editor) (1996) Lancaster University Archaeological Unit

Roman Lancashire, W. Thompson Watkin (1883/2007) Azora Books

Iron Age Communities in Britain, Barry Cunliffe (1975) Book Club Associates London