id: sig-20260722-report-fl130
site_id: gb-dyserth-dyserth
attribute: designation_report
value: 'Reference Number

  FL130

  Name

  Dyserth Castle

  Date of Designation

  Status

  Designated

  Unitary Authority

  Denbighshire

  Community

  Dyserth

  Easting

  306034

  Northing

  379922

  Broad Class

  Defence

  Site Type

  Castle

  Period

  Medieval

  The monument comprises the remains of the outer defences of an important but short lived
  stone castle established by Henry III in 1241 following a documented false start on nearby
  Graig Fawr and comprehensively destroyed by Llywelyn ap Grufudd in 1263. Most of the inner
  ward and the rock below it was destroyed by quarrying during the First World War but its
  general layout is known from an antiquarian survey published in 1912.

  It was located on a towering limestone rock overlooking the eastern bank of the lower reaches
  of the River Clwyd and comprised a compact, irregular inner ward at the highest point of
  the site a with rectangular outer ward on lower ground blocking the approach from the east
  and a smaller crescentic outwork to the west, the remaining sides being defended by precipitous
  slopes. The inner ward comprised an unusual west-facing gatehouse, apparently flanked by
  one round and one polygonal tower at its eastern side, two large polygonal towers facing
  north opposite a domestic range, presumed to be a hall and chambers. There were a series
  of slighter outworks and buildings to the west and south, almost all of which have been
  completely quarried away, with the exception of the western tip of the crescent shaped enclosure
  and its scarped rocky defences. The surviving outer ward is defined by a stony bank and
  rock-cut ditch to the north and east, where it is currently entered from a causeway crossing
  the ditch. There is now a tennis court to the northern side of the interior.Whilst a number
  of articulated fragments of well-mortared limestone masonry survive around the base of the
  hill there is no upstanding stonework, although the outer ward bank may represent the base
  of a wall and the buried lower stages of a square tower and curtain wall shown on early
  plans may survive in the remaining portion of the western enclosure.

  Along with the extensive rebuilding of the ancient Welsh seat of Deganwy some 15 miles to
  the west Dyserth Castle is of historical and archaeological significance as one of two just
  new castles begun in Wales by Henry III of England. These were intended to support Henry''s
  abortive invasion of Gwynedd and to control the disputed Perfeddwlad (the land between the
  Conwy and the Dee), and whilst building works are documented at Dyserth into the 1250s the
  two castles spent most of the decade under an intermittent state of siege until their eventual
  capture and destruction by Llywelyn. Although the relatively recent destruction of most
  of Dyserth''s inner ward represents a great loss, the surviving outer ward and outworks
  are of national importance as the remains of a documented Royal castle with a very limited
  period of use that formed a precursor to the great campaign castle of his son Edward I.
  The remaining portions are likely to retain significant buried structural evidence and associated
  deposits with potential to enhance our knowledge of the construction, development and use
  of the castle and more widely of elite medieval military architecture and domestic practices
  in Wales and beyond. It may also retain artefactual evidence of material culture dateable
  to a closely documented period, along with environmental evidence of the use of the castle
  and its contemporary medieval landscape.

  The scheduled are comprises the remains described and areas around them within which related
  evidence may be expected to survive.'
source_url: http://cadwpublic-api.azurewebsites.net/reports/sam/FullReport?lang=en&id=640
source_title: Scheduled Monument Full Report — Dyserth Castle
publisher: Cadw
observed_date: '2026-07-22'
collected_by: scripts/build_assessment_batch.py
confidence: high
notes: The designation text. Assess the six bands against THIS evidence only; omit any band
  it does not speak to.