Knowth is both the largest and most remarkable ancient monument in Ireland. Though Newgrange is more famous and Dowth is probably older, Knowth has proven to be a fascinating and important site with a collection of more than 400 engraved stones and some finely carved artifcts dating from the neolithic, some 5,200 years ago.
The main mound is surrounded by at least eighteen smaller structures, many of which have or had engraved slabs. Some of the satellite mounds, whichs are as large as twenty meters in diameter, predate the huge mound. In Irish mythology Knowth is Cnoc Bui, home to the sovereignty Goddes Bui, consort of Lugh of the Long Arm.
Knowth is located on a ridge 2 km north-west of Newgrange, and is the closest of the three mounds to the River Boyne. It is the largest chambered cairn in Ireland with a diameter of 95 by 85 m, and covers more than an acre of ground. The mound has two passages and chambers which were re-opened during excavations by, George Eogan in the late 1960's. The east and west passages of Knowth are the longest megalithic passages in Europe, with many fine engravings on the orthostats and roofslabs. A continous ring of 127 kerbstones encircles the base of the great mound.
Access to Knowth is only possible from the Bru na Boinne visitor center across the river; shuttle busses bring visitors to and from the site. A tour of the site lasts about an hour. The passages are not open to the public; visitors are taken instead into a concrete bunker built into the east side of the mound.
Knowth has the largest collection of megalithic art known from neolithic western Europe, and accounts for half of the total number of engraved megalithic stones in Ireland. Knowth's artwork is the equivelant of a huge library of the stone age world, perhaps part of the neolithic university of the ancient Boyne Valley. Almost all of the kerbstones encircling the large mound are engraved, many with what seem to be obvious solar and lunar symbols.
The mound was under investigation for 40 years, with excavations beginning in June 1962 and proceeding every year until 2002, when the site open to the public. The excavations, carried out by professor George Eogan and his team, found that the site had remained in continous use from the stone age to the middle ages, with 12 sequences of use. The satellites pre-date the large mound, and the foundations of several neolithic houses were also found under the mound.
The main mound was completely removed, which is a pity, as the mound builders had gone to great trouble to build the mound in layers. Something like five acres of fine grass land was stripped to provide the base for the mound.
Much of the removed material was replaced with modern building materials: cement, styrafoam and putty! The structural stones, several hundreds of them, all of a hard type of stone called greywackie, were dragged at least 6 km from their quarry.
Likewise, round granite cobbles were collected from the shore around around the Cooley peninsula, some 60 km to the north, and the chunks of quartz found spread around the entrances came from Wicklow, 60 km to the south.
In 1967, while investigating a medieval souterrain, the excavators discovered the entrance to the West Passage.