New and exciting archaeological finds have been made at the Knowth tumulus over the last few months, according to archaeologists working on the site. The passage tomb cemetery at Brú na Binne has produced some extraordinary discoveries over the decades ever since Professor George Eogan made his first tentative exploration in and around the site. A number of previously unknown large-scale monuments in the field lying immediately to the south-east of the large mound have recently come to light. A programme of detailed non-invasive topographical, electrical resistance and magnetometer surveys conducted by Joe Fenwick of the archaeology department of NUI Galway, in collaboration with Professor George Eogan, has revealed a complexity of sub-surface wall-footings, earth-filled ditches and post-pits. This research confirms that the archaeological footprint of Knowth extends over a far greater area than previously thought. The nature, date and function of these 'hidden' monuments has yet to be fully assessed but it is likely these features represent a succession of overlapping periods of human occupation, building and rebuilding over the course of several thousand years - from the early Neolithic up to the present day. Two features are particularly apparent in the magnetometer image, a large double-ringed oval measuring 65m across its minor axis and a sub-rectangular ditched enclosure with internal features measuring over 70m in maximum dimension. These may represent the remains of a double-ditched enclosure of prehistoric or early medieval date, possibly a henge-like enclosure or ringfort, and a medieval or post-medieval walled enclosure, respectively. In the absence of dating evidence and with few, if any, definitive archaeological parallels, only very tentative interpretations of these features can be provided at this early stage of investigation, the archaeologists said. During OPW repair works to a 19th century wall, which forms a boundary along the west side of the public road, a number of significant stones that had been built into its fabric were identified. One, though undecorated, is likely to have served as kerbstone marking the base to one of Knowth's satellite tombs. Another is an architectural fragment, possibly part of a chapel or other prominent structure at Knowth, which once formed part a grange established in the high medieval period by the Cistercian monks of Mellifont. Perhaps the most remarkable discovery, however, is a stone which bears a finely carved spiral in the megalithic tradition on one of its surfaces - undoubtedly a structural stone from one of the nearby small passage tombs.