About the model
The great mound at Knowth (Tomb 1), built and used c. 3200-2900 BC, is subcircular (95 m N-S, 80 m E-W, 10 m high) with a kerb of 127 contiguous kerbstones, most of them decorated, and covers two back-to-back passage tombs whose chambers are about 5 m apart: the eastern tomb (40.2 m long, a straight passage to a cruciform chamber with a corbelled vault 6.1 m high) and the western tomb (34.2 m, a passage bending 19-20° about 25-27 m in, to an undifferentiated chamber). Built in phases (1A dismantled; 1B the two chambers with short passages in a 38 m cairn; 1C passages lengthened to a new kerb under the great mound). In the early medieval period the mound became a rath and the passage ends were cut by ditches and souterrains, so the original entrances are lost. Excavated by George Eogan 1962-2000; the entrances were reconstructed and closed (concrete), the passages encased and propped, and the chambers are closed to visitors. The equinox alignment often claimed has been tested and rejected by Prendergast and Ray.