2025:511 - Clonoghil Castle, Clonoghil Upper, Offaly

In June-August 2025, the IHS (Irish Heritage School, formerly trading as the Irish Archaeology Field School (IAFS)) undertook an excavation at Clonoghil Castle, Clonoghil Upper townland in Co. Offaly. This was the second season of excavations at the site, following an initial season in June-August 2024.

Clonoghil Castle, located 1.6km outside of Birr Town, is in the ownership of the Offaly County Council (OCC) and is a recorded monument (OF035-014001 (castle) and OF035-014004 (bawn)) protected under the National Monuments Acts 1930-2014.

Clonoghil contains a stone castle, speculated to be a hall house, surrounded by an earthen bawn. Prior to excavation the earthen ‘bawn’ was of uncertain date and has variously been associated with an earlier repurposed ringfort, later medieval bawn and seventeenth-century defences. The excavation, run as a research dig, aimed to date both the stone castle and earthen bawn (as well as assess their form and function).

In 2024, two cuttings were opened at the site. Cutting 1 was excavated across the south-eastern side of the monument where the ditch and bank are most obvious, whilst Cutting 2 was excavated on the internal south-east angle of the castle, where an observed internal wall cupboard gave some indication as to the depth of any likely floor surface. In 2025 a single cutting, Cutting 3, was excavated immediately south of the visible masonry remains where an entrance hall would most likely be located. No archaeological excavation was undertaken outside the monuments, as geophysical surveys by the IHS and OCC at Clonoghil in 2023 (undertaken by Ger Dowling: Detection Device Registration No. 23R0024) indicated the landscape surrounding the castle is largely devoid of archaeology; this finding was consistent with results of archaeological testing conducted by David Sweetman in 2006 at the western limit of the field containing Clonoghil.

In a near absence of material cultural items from the site (notably medieval cultural remains) the excavations revealed little evidence of medieval society at the site in terms of diet, economy etc. However, careful architectural recording of the castle in 2024 indicated that both typologically and structurally the remains are most likely to be a thirteenth- to fourteenth-century hall house. This speculated date of the castle was confirmed by returned radiocarbon dates since the 2024 excavation; an internal burnt feature within the building has been dated to 1281-1388 cal AD, while the basal fill of the enclosing ditch/earthwork was dated to 1284-1393 cal AD. Whilst these dates confirmed the conjectured thirteenth- to fourteenth-century date, a definitive typology of the castle was not established, leading to further excavations in 2025. Although specialist analyses continue, the 2025 investigations further point toward Clonoghil belonging to the hall house class of medieval castle, with a possible hall measuring 2.6m in width likely being attached to the main structure.

The hall house at large appears to have been altered, most likely in the seventeenth century, when chimneys and possible red-brick windows or reveals were added – subtle archaeological evidence of which remains on site in the form of rubbles containing brick. As stated, the enclosure whilst now confirmed as a later medieval bawn, appears to have fulfilled different functions or been altered through time, with the ditch seemingly recut and the bank extended sometime in the seventeenth to nineteenth century (most likely in association to the site being placed under siege in the seventeenth century).

The excavations at Clonoghil are part of a much wider public heritage programme of research entitled Monastic Midlands. This landscape-scale project is a partnership between the IHS, OCC and several local communities in Co. Offaly and includes research at several sites such as Seir Kieran, Killeigh, Birr and Lemanaghan. A key part of this community project for Clonoghil is to see the site conserved and also included as part of a looped heritage walk within the town of Birr.