Ancient Monuments

History on the Ground

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Byrllysg promontory fort

A Scheduled Monument in Dyffryn Ardudwy, Gwynedd

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Latitude: 52.7962 / 52°47'46"N

Longitude: -4.0839 / 4°5'2"W

OS Eastings: 259591

OS Northings: 324101

OS Grid: SH595241

Mapcode National: GBR 5R.WY5W

Mapcode Global: WH566.7ZJ8

Entry Name: Byrllysg promontory fort

Scheduled Date:

Source: Cadw

Source ID: 277

Cadw Legacy ID: ME064

Schedule Class: Defence

Category: Promontory Fort - inland

Period: Prehistoric

County: Gwynedd

Community: Dyffryn Ardudwy

Traditional County: Merionethshire


The monument comprises an impressive small inland promontory fort, probably dating to the Iron Age (c. 800 BC - 74 AD the Roman conquest of Wales) and situated on a convenient spur at the head of a small valley and above the confluence of two streams. The fort measures about 60m in diameter within its defences. A partial stony bank at the leading edge of the scarp defines the N, W and S sides; and a substantial earthwork rampart and ditch protects the E side of the fort. The interior is relatively even and it is possible that elements of the terrace are artificial. The fort is overlain on the S by a ruinous drystone cottage, on the NE by the remains of a drystone sheepfold and around its circuit by several field walls. Although no interior features are visible, a result of clearance and cultivation in the past, this is a fine example of a small, easily defended inland promontory fort.

The monument is of national importance for its potential to enhance our knowledge of later prehistoric defensive organisation. The monument forms an important element within the wider Iron Age context and the interior, rampart and ditch may be expected to contain archaeological information in regard to chronology, building techniques and functional detail. The association with later (now deserted) settlement further enhances its archaeological and historical potential.

The area scheduled comprises the remains described and an area around them within which related evidence may be expected to survive. It is broadly circular and measures 80m in diameter.

Source: Cadw

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