The hook
A grass-covered stone mound built around 3200 BC, older than Stonehenge and the Egyptian pyramids, engineered so that at the winter solstice a beam of sunrise light runs straight down a long passage into the burial chamber.
01Why it's worth it
Newgrange is a Neolithic passage tomb, a huge circular mound faced in white quartz, ringed by kerbstones carved with spirals whose meaning we have lost. It was raised more than five thousand years ago by a farming society with no metal tools, and its builders got one thing exactly right: a slot above the entrance, the roof-box, is aligned so that for a few mornings around the winter solstice the rising sun sends a shaft of light down the nineteen-metre passage to illuminate the inner chamber. The rest of the year a guide simulates the effect with a lamp, and even the simulation, standing inside a dark five-thousand-year-old room, is quietly staggering. It is part of Brú na Bóinne, a whole complex of tombs in a bend of the river Boyne, and it changes what you assume "ancient" means in western Europe.
02How to experience it
You can only enter on a guided tour by shuttle from the Brú na Bóinne visitor centre, so book ahead in season. Actual presence in the chamber at dawn on the solstice is allotted by an annual lottery for a handful of places. Pair it with the neighbouring tomb at Knowth, which has the richest concentration of megalithic art.