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Cof Cymru: National Historic Assets of Wales · Wales

Dinas Dinlle Seagull Trench

Llandwrog, Gwynedd, Wales

The record

Designation
Scheduled monument
Site type
Seagull Trench
Period
Modern
Date of designation
8 June 2006
Community
Llandwrog
Unitary authority
Gwynedd
Country
Wales
Coordinates (centre of the scheduled area)
53.08311, -4.33536
SAM number
CN396
Cadw record number
1168

Slide toward Today to fade the historical sheet and see the modern map underneath.

David Rumsey Map Collection, Stanford Libraries

Shown on 5 historical map sheets, the earliest the 1883 "Watershed map England, Wales 3." (David Rumsey Map Collection, Stanford Libraries).

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This record in Cadw's own full report ↗

Cadw's description

The following provides a general description of the Scheduled Monument.

The monument comprises a seagull trench, a partially buried defensive structure dating to World War II (AD 1939-45). It is embedded into the bottom of a steep N facing slope in an enclosed field of pasture. The structure is mostly subterranean and consists of five compartments with only a concrete roof and ten embrasures visible externally. The seagull trench measures 22.4m long, c.4m deep and c.2.5m tall. It is aligned ENE-WSW. An entrance and associated tunnel lie to the S. Its name is derived from its shape on plan which resembles a bird.

The monument is of national importance for its potential to enhance our knowledge of World War II defensive practices. Further, this example is a rare occurrence of this site type in Wales. The monument is well preserved and is an important relic of the perimeter defences of the former RAF station at Llandwrog. It retains significant archaeological potential, with a strong probability of the presence of associated archaeological features and deposits.

The scheduled area comprises the remains described and an area around them within which related evidence may be expected to survive. It is rectangular and measures 26m E-W by 12m transversely.

Nearby in the register

Other entries of the same register within about three miles of this one, by straight line.

Designated Historic Asset GIS Data, The Welsh Historic Environment Service (Cadw), 2026-09-07, licensed under the Open Government Licence http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/ Cadw, the Welsh Historic Environment Service · Open Government Licence v3.0
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