Knowth (/ n aʊ θ /; Irish: Cnóbha ) is a Neolithic passage grave and an ancient monument of the world heritage of Brú na Bóinne in Ireland valley of the River Boyne. It is the largest passage grave of the Brú na Bóinne complex and consists of a large mound (known as Site 1) and 17 smaller satellite tombs. The mound is about 12 meters (40 feet) high and 67 meters (220 feet) in diameter,  which covers about a hectare. It contains two passages, placed along an east-west line and surrounded by 127 kerbstones, three missing, and four seriously injured.
The large stack has been estimated to date from 2500 to 2000 BC.  The passages are independent of each other, leading to separate tomb. The eastern passage arrives at a cross-chamber, similar to the one at Newgrange, which contains three recesses and basin stones into which the cremated remains of the dead placerades.Den right recess is larger and more elaborately decorated with megalithic art than the other, which is typically Irish passage graves of this type. The western passage terminates in an undifferentiated chamber which is separated from the passage of a threshold stone. The chamber seems to have also contained a basin stone which was later removed and is now located about two-thirds down the passage.
Knowth contains more than one third of the total number of examples of megalithic art in the whole of Western Europe, [ citation needed ] over 200 decorated stones were found at utgrävningar.En large part of the artwork on the curbs, especially approaching the entrances to the passages. Many of the motifs are typical: spirals, lozenges and serpentiform. But the megalithic art at Knowth contains a variety of images, such as crescent shapes.Interestingly, much of this work of art was carved at the expense of the stones; a type of megalithic technique known as hidden art. This suggests all sorts of theories regarding the function of megalithic art in the Neolithic society that built the monuments in the Boyne Valley. It is possible that they thought the art of hidden. It is also possible that the blocks simply recycled and reused in the other.
There is some evidence for late Neolithic and Bronze Age activity on the site.Most of this is because there is a grooved ware timber circle located near the entrance to the eastern passage. Archaeological evidence suggests that this was used as a ritual or sacred area after the great mound of Knowth had already been forgotten. Evidence for the ritual consists of a large number of offerings available in and around the immediate areas of the timbers that formed the circle.
The hill at Knowth canceled, and the pile or heap slipped, which allows inputs to both passages to be covered. The place remained virtually unused for a period of two thousand years. The place was short as a burial place;some 35 coffin graves found at the site during excavations.  These seem to be Celtic burials.
In the late Iron Age and early Christian times, there was an ancient castle with enclosing ditches and Souterrains added. Knowth became a habitational place for the first time. Two trenches dug, at the base of a pile behind the curb, and the other at the top. At this stage, the inputs of both passages appears to have discovered. Evidence found early Christian graffiti on the rocks in the eastern chamber, and four names were carved in Ogham. It seems it was at this stage that the stone basin from the western chamber was moved in an attempt to remove it and was abandoned in the passage because it got stuck. Knowth became a significant political space and the capital of the Kingdom of Northern Brega. 
After a brief military interlude after the Norman invasion of Ireland, when the Normans used Knowth as a motte in the 12th century, the site was occupied by the Cistercian monks iMellifont Abbey. It seems that the pile again used as a grange or farm. Stone walls were built over the mound, and stone buildings inside the walls. After the dissolution of the monasteries, the site was mainly used for farming until most of the site was taken over by the state in 1939.
A historical reference to the cave is to be found in the triads in Ireland, dating from the 14th to the 19th century, where ” UAM Chnogba , UAM Slángæ andDearc Fearna ” listed under the heading “the three darkest places in Ireland”. [ 4] the last, that is, “the cave of the Alders,” is generally thought to be the current Dunmore Cave,  while the first two translate as caves of Knowth and caves of the Slaney.  it is not known exactly the cave system / passage tombs near the river Slaney is being referred to, with the most likely, they Baltinglass. Other sources translate the listed places Rath Croghan, cave or crypt Slane  and the “Cave of the Ferns”. 
The east-west direction of the passages at Knowth proposes astronomical line with the equinoxes. The focus of Knowth is not present today. This depends on a number of factors. First of all, the passages were discovered by later settlers, and was, to some extent, destroyed or incorporated Souterrains. In this way, the original entrances to the passages were distorted or destroyed, making it difficult to determine whether an adaptation ever existed. Furthermore, the recent excavations (1962 onwards) under George Eogan resulted in the construction of a concrete slab wall inside the piles west entrance, limit any investigation of possible adaptations. It seems likely that the passage was intended to adapt. Moreover, adaptations of ancient monuments change due to Milankovitch cycles.
A short excavation of the site was conducted in 1941 by MACALLISTER. But large full-scale excavations began at the site in 1962 and was conducted by George Eogan of University College Dublin. When his excavations began, very little is known about the full extent of the site. The entrances to the western and eastern passages were discovered in 1967 and 1968 respectively, and, slowly, the layers of activity at the site of Knowth were detected. The excavation has produced a large number of books and reports on the results.The archaeological site of Knowth East ended any chance to research on changes when George Eogan erected a concrete wall across the east-passage entrance. The most extensive research on changes and astronomy at Knowth was carried out by American-Irish researcher Martin Brennan. 
Access is by guided tour only. Tours begin at the Brú na Bóinne Visitor Centre in Donore. Visitors can look down the eastern passage and visit the nearby modern interpretive room.
- ^ Jump up to: ab Harbison, Peter. (1970). Guide to the National Monument of Ireland. Gill & Macmillan.
- Jump up ^ O’Brien, Elizabeth. “Post-Roman Britain to Anglo-Saxon England”. British Archaeological Reports , 1999. 27. ISBN 978-1-8417-1118-8
- Jump up ^ Stout, Geraldine. “Newgrange and the Boyne Bend”. Cork: Cork University Press, 2002. 76. ISBN 978-1-8591-8341-0
- Jump up ^ Meyer, Kuno; Lavelle, Hilary; Purcell, Emer; et al., eds.(2005). Triads in Ireland. Todd Lecture. 13 (1st ed.). Dublin: Hodges, Figgis & Co.. Taken 2010-11-06.
- Jump up ^ Coleman, JC (1965). The caves in Ireland. Tralee, Co. Kerry: Anvil Press. pp. 14-16.
- ^ Jump up to: ab Meyer, Kuno, ed. (1906). Triads in Ireland. Todd Lecture.13 (1st ed.). Dublin: Hodges, pp Figgis & Co. 4-5. . Retrieved 2010-11-06.
- Jump up ^ Foot, Arthur Wynne (1878). “An account of a visit to the cave Dunmore, Co. Kilkenny, with some comments on human remains found there. ” Journal of the Royal Society of Antiquaries of Ireland. 4. Dublin. In: 65-94. Retrieved 2010-11-06.
- Jump up ^ Stars and Stones later be published as stones Time: calendars, sundials and Stone Chambers of Ancient Ireland , 1994 [ISBN 978-0-8928-1509-8 or ISBN 0-89281-509-4]