id: sig-20260722-report-mm109
site_id: gb-llangybi-llangibby-tregrug
attribute: designation_report
value: 'Reference Number

  MM109

  Name

  Llangibby Castle (Castell Tregrug)

  Date of Designation

  05/09/1950

  Status

  Designated

  Unitary Authority

  Monmouthshire

  Community

  Llangybi

  Easting

  336397

  Northing

  197408

  Broad Class

  Defence

  Site Type

  Castle

  Period

  Medieval

  The following provides a general summary of the Scheduled Ancient Monument.

  The monument consists of the remains of a castle, dating to the medieval period. The castle
  was built by the De Clare family in the 13th century, but is thought to have been unfinished
  when Gilbert de Clare V was killed at Bannockburn in 1314. The site consists of a large
  oblong bailey, 160m long by 80m wide, surrounded by a curtain wall that is largely complete
  to battlement level. There is an entrance into the bailey at the E end of the site. The
  entrance is 3.5m wide and has the remains of round towers on either side - the N round tower
  only survives as a curved wall, while the S tower is complete and stands to a height of
  5m. The walls of the tower are 3m thick. The curtain wall on the E side survives in short
  stretches, one to the N of the entrance and three to the S. These sections of curtain wall
  stand to between 1.2m and 5m high on the inside, and up to 2m higher on the outside, and
  retain many original facing stones. On the S side of the site, there is a short stretch
  of curtain wall, 12m long and 3m high, at the E end. To the W of this section of wall is
  a 50m wide gap before a long stretch of curtain wall. In the gap there is a low scarp. The
  long section of walling is 30m long and 3.5m high, and has putlog holes for supporting timber
  buildings on its inside. In the SW corner of the bailey are the remains of a large tower,
  6m high on the outside, with a large arched opening on the S side and the remains of a spiral
  staircase. Adjacent to the tower are the remains of a series of room. To the N of this tower
  is a 20m long, 2.5m wide entrance passage, with standing walls 3.5m high. To the N of the
  entrance is a round tower, 3.5m high, with a room behind it. A well-preserved doorway survives
  to the N of the tower. It is 1.8m wide and has a dressed stone wall behind it. To the N
  of the tower the curtain wall becomes more ruinous and the peters out. In the NW corner
  are the remains of a rectangular keep with towers at its corners. The tower in the SW corner
  is massive, 6m high with facing stones surviving for much of its height. The NW corner tower
  is 5.5m high with most of the facing stones missing. Large sections of fallen walling lie
  on the ground to the W of the tower. Inside the W end of the rectangular keep are two large
  arches with two smaller ones on either side. On the S side there are portions of ashlared
  vaulting on the roof of the room. At the E end there is a large central arch through the
  keep wall, with round towers on either side, each with an arch into it. The walls are up
  to 3.5m high and retain much of their faced stone. There is a further vaulted roof in the
  NE tower, which has a six-sided interior and two steps on the SE side. On the N side of
  the castle the curtain wall is continuous, 3m high on the inside and 4m high on the outside.
  There are putlog holes in the N wall and the stonework is in good condition. In the centre
  of the N side are the remains of a round tower standing 2m high with 2m thick walls. There
  are gaps in the middle on each side. The curtain wall ends abruptly at the NE corner of
  the castle.

  On the W side of the castle the ground drops steeply down to a deep ditch, part of which
  forms a sheer rock face 3m high. Outside the ditch is a narrow berm and a bank, varying
  in height between 1.6m and 3m. At the S end of the bank there is a gap for a modern track,
  after which is continues along the S side of the site. On the N side of the castle the ground
  drops sharply away.

  The monument is of national importance for its potential to enhance our knowledge of medieval
  defensive practices. The monument is well-preserved and an important relic of the medieval
  landscape. It retains significant archaeological potential, with a strong probability of
  the presence of both structural evidence and intact associated deposits.

  The scheduled area 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=365
source_title: Scheduled Monument Full Report — Llangibby Castle (Castell Tregrug)
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.