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Ruined Undercroft at St Mary's Abbey

A Grade I Listed Building in Margam, Neath Port Talbot

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Latitude: 51.5622 / 51°33'44"N

Longitude: -3.7298 / 3°43'47"W

OS Eastings: 280193

OS Northings: 186235

OS Grid: SS801862

Mapcode National: GBR H6.DSMH

Mapcode Global: VH5H2.9ZLS

Plus Code: 9C3RH76C+V3

Entry Name: Ruined Undercroft at St Mary's Abbey

Listing Date: 12 November 1952

Last Amended: 25 April 2000

Grade: I

Source: Cadw

Source ID: 14150

Building Class: Religious, Ritual and Funerary

Location: Located to the S of the Chapter House and E of Margam Orangery.

County: Neath Port Talbot

Town: Port Talbot

Community: Margam

Community: Margam

Locality: Margam Park

Traditional County: Glamorgan

Tagged with: Building

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Robert of Gloucester, Earl of Glamorgan, granted lands for a Cistercian Abbey at Margam in 1147. Most of the nave of the original C12 abbey church survives and is now the parish church. The rest of the abbey church and the remaining monastic buildings were rebuilt in Early English style in the early C13, probably in 1203-13 under Abbot Gilbert. The undercroft belongs to this phase. It supported a storey above, probably a bridge leading to the monks' dormitory at right angles to the W. Alternatively, the upper storey could have been part of the dormitory or even an infirmary, although the latter is likely to have been in a more isolated position.

Margam Abbey was dissolved by the crown visitors of Henry VIII in 1536-7 and the monks evicted. By 1540, Sir Rice Mansel (1487-1859) of Oxwich and Old Beaupre had acquired most of the former monastic lands. He built an impressive Tudor house, incorporating some of the monastic remains into the service areas.


Three-bay vaulted structure orientated E-W of roughly coursed stone with quoins. Arcade of 3 pointed arches surviving to just above apex level, but the E arch of the N side is no longer extant. Low impost band to arches, chamfered to underside. Pilasters to fronts of piers. Wide arches to E and W ends, the dressings no longer surviving. The E piers are built into short N-S walls with quoins, possibly demarcating a corridor or range beyond. A break in this wall further N suggests a doorway. Large pier or wall fragment against N side of NW pier, while a short wall joins the W side of the SW pier. Quadripartite ribbed vaults survive to the W and central bays. Low scalloped corbels between the vaults support chamfered ribs.

Reasons for Listing

Listed grade I as a rare survival in S Wales of a medieval monastic building. Group value with Abbey Church of St Mary and chapter house.

Scheduled Ancient Monument GM005 (NEP).

External Links

External links are from the relevant listing authority and, where applicable, Wikidata. Wikidata IDs may be related buildings as well as this specific building. If you want to add or update a link, you will need to do so by editing the Wikidata entry.

Recommended Books

Other nearby listed buildings

  • I Ruins of Chapter House and Vestibule of St Mary's Abbey
    Located in a central position in the gardens at Margam Park, to the NE of the orangery.
  • I St Mary's Abbey Church
    Located at the end of a short lane which runs NE off the A48. The Stones Museum is within the churchyard. The S doorway faces into Margam Park.
  • I Margam Orangery
    The centre-piece in the gardens at Margam Park. The abbey remains are immediately to the NE, with the broadwalk leading up to Margam Castle further E.
  • II* Terrace with Pools and Flower Beds Fronting Margam Orangery
    Immediately in front of and adjoining Margam Orangery.
  • II Broadwalk Steps
    Located near the W end of the broadwalk, E of the orangery and chapter house. The broadwalk rises up to the E with Margam Castle as the focal point.
  • II War Memorial
    Located immediately outside and to the R of the entrance gates to St Mary's Abbey Church and churchyard.
  • II Arch over Culvert
    The culvert receives water from the cascade to the NE, beyond which is the lake. The ground slopes down sharply to the S but becomes flatter where the water passes underground.
  • II Churchyard Walls and Gate Piers to St Mary's Abbey Church
    Enclosure walls to a large, roughly rectangular churchyard to the N of the abbey church. It projects round to the W and incorporates the entrance gates.

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