Fourknocks is a small and beautiful neolithic site near the village of Naul in north Co. Dublin. There are the remains of four chambered cairns found on a hill, the four 'Cnocs' or 'little hills' of the name Fourknocks. The hill is 152 meters above sea level, and is located about 14 km south east of the Boyne Valley.
One site, probably the main mound, has been restored, and resembles somewhat the Mound of the Hostages at Tara nearby. The remaining three monuments, which are in nearby fields are quite ruined. One has a long pit or trench which was filled with bone ash, and may have been a cremation pit.
The main site of Fourknocks turned up some interesting information and finds when it was excavated by Harnett in 1950. Fourknocks is closed by a modern door, the key to which can be obtained from the nearest house. The chamber is entered by a short passage which is oriented to about 15° east of north, too far north for the sun or moon to enter, and probably aligned to the rising of a constellation.
There is a large pear-shaped chamber within the mound, the largest discovered so far in Ireland. Normal corbelling would hardly have been able to span this space which measures 6.5 x 5.5 meters. A posthole at the centre suggests that a central pole and possibly a wooden and thatched roof covered the structure. The modern reconstruction has covered the chamber with a concrete dome, with small shafts which allow natural light to enter. There are three recesses placed about the rear of the chamber, and the lintel of each recess is engraved.
There are several beautiful pieces of megalithic art within the chamber. The lozange/diamond shape was popular here, and three stones are covered in variations of the diamond and zig-zags. Another is a complete study on the zig-zag and seems quite related to the art at Newgrange, while another is composed of circular designs.
Another again has sctatched designs which some have taken as evidence of zoomorphic art due to it's slight resemblance to a face. The circular designs, however do resemble pebble and sand drawings made by native Australian shamen.