Ancient Monuments

History on the Ground

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Ynys y Castell

A Scheduled Monument in Mathry (Mathri), Pembrokeshire (Sir Benfro)

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Latitude: 51.9622 / 51°57'43"N

Longitude: -5.129 / 5°7'44"W

OS Eastings: 185124

OS Northings: 233924

OS Grid: SM851339

Mapcode National: GBR CC.LGG3

Mapcode Global: VH1QK.1YV5

Entry Name: Ynys y Castell

Scheduled Date:

Source: Cadw

Source ID: 3020

Cadw Legacy ID: PE038

Schedule Class: Defence

Category: Hillfort

Period: Prehistoric

County: Pembrokeshire (Sir Benfro)

Community: Mathry (Mathri)

Traditional County: Pembrokeshire


The monument comprises the remains of an earthwork enclosure and possible settlement on a craggy tidal islet at the mouth of Abercastle Bay. The date or precise nature of the remains is unknown, but they are likely to be later prehistoric or medieval. The summit is enclosed by two lines of slight bank; one passing from cliff to cliff in a straight line on the north east and another, which is L- shaped, following the cliff top west before turning to cross to the cliff at the east. Within the enclosed area of about 30m square are traces of possible hut scoops whilst others are located on the slope to the south west including a larger indentation of c 12m x 8m known as 'Bedd Bys Sampson'.

The monument is of national importance for its potential to enhance our knowledge of later prehistoric defensive organisation and settlement. The site forms an important element within the wider later prehistoric context and within the surrounding landscape. The site is well preserved and retains considerable archaeological potential. There is a strong probability of the presence of evidence relating to chronology, building techniques and functional detail.

The scheduled area comprises the remains described and areas around them within which related evidence may be expected to survive.

Source: Cadw

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