The Boyne Valley and its surroundings, situated in a loop of the River Boyne, some 20 miles northwest from Dublin, a few miles west of Drogheda, County Meath, is one of the most important Irish locations as far as an historical heritage is concerned, from pre-Celtic to medieval times. In this area you can find the pre-Celtic tumula of Newgrange, Knowth and Dowth, the Hill of Tara, where the ancient Irish kings settled their kingdom (actually, there is not much to see in Tara nowadays, but the site is inspiring), Monasterboice with its High Crosses, the Mellifont Abbey and many other interesting things.
Newgrange is the best known Irish passage tomb. It was constructed around 3200 BC, making it more than 500 years older than the Giza Pyramids in Egypt and 1000 years more ancient than Stonehenge. It is about 80 meters in diameter, surounded by a kerb of 97 stones. Some of these are elaborately carved. Inside the mound is a passageway lined with roughly-hewn stone slabs that leads to a cross-shaped chamber.
The entrance to the passage is a simple doorway formed by two upright slabs and a horizontal lintel. Above the doorway is a hole known as the roofbox. The passageway has an amazing feature: although built from roughly-hewn rock, it is aligned in such a way that the rising sun shines through the roofbox, down the passageway and lights up the central chamber on the morning of the Winter Solstice (21 or 22 December). This amazing fact was only discovered during the 19th century, verified scientifically around 1960. While initially dismissed as coincidence, it is now generally accepted that the mound was designed with this in mind. It shows that the people of 5000 years ago were far more sophisticated than we generally think.
Newgrange is open to the public by guided tour only. Visitors must report to the Brú na Bóinne Visitor Centre on the opposite side of the River Boyne, where they walk across a pedestrian bridge and are brought by coach to the site.
Knowth is less well known than Newgrange, actually slightly bigger, being about 84 meters in diameter. The great mound of this most spectacular site is outlined by 127 massive kerbstones. There are two passages, aligned to face East and West. The west-facing one is an unbranching curved passage. The east-facing one is cross-shaped and similar to the one in Newgrange. It is claimed that these passages are aligned with the position of the rising and setting sun at the two equinoxes. This claim is not generally accepted and has not been verified.
Knowth has a huge amount of stone carvings. It is reckoned that one quarter of all Europe's neolithic art is held within Knowth! The same spirals appear throughout Knowth, as well as other patterns based on diamonds and chevrons.
While some people dispute the fact that the primary purpose of these mounds was as tombs, there is no doubt that many people were interred there. The remains of 200 people were discovered in Knowth. The stone age practise was to cremate the bodies outside, then place the remains in a hollow in a special stone within the burial chamber called the basin stone. The basin stone in Knowth's western passage is no longer in the burial chamber. In 1000 AD, somebody tried to remove it from the mound, not realising it was bigger than the passage. It got stuck in the passage and remains there to this day.