Magnetic survey was requested for an area adjacent to Castle Warren House, Barnahely to determine whether there was sufficient archaeological material to influence route selection for part of the new N28 Bloomfield to Ringaskiddy road. The survey was able to demonstrate that the highest parts of the hillside contain substantial quantities of buried features, many presumed to be of prehistoric date, others perhaps related to the medieval and post-medieval occupation of the site. This spread of activity includes elements of early settlement and large enclosures, some with ditches perhaps 2m wide, as was found to continue northwards into the adjacent field on the hilltop. Next to the castle itself survey proved impossible for a variety of reasons. These include the installation of a high pressure gas main around two sides of the monument, a main sewer, inspection chamber and associated works, the presence of demolished concrete and steel outbuildings and significant quantities of steel debris throughout the topsoil. Visual inspection of the site, however, revealed masonry footings at various locations, including the remains of the walled garden to the east and other structures immediately adjacent to and north of this, the latter not depicted on the 1st edition Irish Ordnance Survey mapping seen by ArchaeoPhysica. The southernmost regions of the site produced far fewer anomalies of archaeological interest, perhaps due to increased soil erosion on the slope or perhaps because the hilltop was favoured for activity in the past. There are signs, however, of a boundary structure around the southern edge of the field within the current field margin and separate from the extant demesne masonry. There are also signs of a surfaced track along a former boundary aligned north – south within the field that appears to pass through some sort of gateway in this structure. The piecemeal nature of development near the site makes it likely that significant damage to the archaeological resource has already occurred and will perhaps continue to occur. For this reason the overall development context of the proposed road, secondary development and infrastructure related to them needs to be considered if further loss is to be adequately mitigated. Primary Archive held by Cork NRDO. Secondary Archive held by ArchaeoPhysica