Ancient Monuments

History on the Ground

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Caer Idris Hillfort

A Scheduled Monument in Llanidan, Isle of Anglesey (Ynys Môn)

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Latitude: 53.1873 / 53°11'14"N

Longitude: -4.2546 / 4°15'16"W

OS Eastings: 249450

OS Northings: 367957

OS Grid: SH494679

Mapcode National: GBR 5J.3BYP

Mapcode Global: WH437.M46V

Entry Name: Caer Idris Hillfort

Scheduled Date: 3 May 2016

Source: Cadw

Source ID: 2525

Cadw Legacy ID: AN051

Schedule Class: Defence

Category: Hillfort

Period: Prehistoric

County: Isle of Anglesey (Ynys Môn)

Community: Llanidan

Traditional County: Anglesey


A small inland promontory fort which is protected on three sides by stone banks and on the fourth by a natural limestone scarp. The banks were originally semi-circular and terminated at the cliff edge, but a road now runs along the edge, destroying the ends of the banks. The SW and NE parts of the outer banks have also been destroyed where they cross modern field boundaries into a cultivated field on one side and a house and garden on the other.

The fort remains lie within a wooded area with much undergrowth which obscures large parts of the site. The entrance is towards the centre of the semi-circle and gaps in the banks are staggered; these gaps are just over 6 m across. There are remains of four ramparts NE of the entrance and three SW of it. These banks or ramparts vary from 0.25 m high to 1.5 m high, the inner banks being larger than the outer banks. The third outer bank on the NE side contains three upright stones set in the bank near the entrance; they stand about 1 m high.

The monument is of national importance for its potential to enhance our knowledge of Prehistoric settlement and defence. It retains significant archaeological potential, with a strong probability of the presence of associated archaeological features and deposits. The structures themselves may be expected to contain archaeological information concerning chronology and building techniques.

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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