Newgrange, partly because of it’s restoration , is the best-known of the three megalithic mounds ( Newgrange, Knowth, Dowth) of the Boyne Valley in the east of Ireland. The passageway is aligned to sunrise on the shortest day of the year, the light of which comes through the specially constructed light-box over the entrance. Across the entrance lies the richly engraved threshold stone. Engraved kerb stones ring the base of the mound. The façade on either side of the entrance is composed of white quartz stones. At the end of the passage the roof rises into a high vault, composed of ever-decreasing circles of stone slabs (corbelling). The remains of a circle of standing stones ring the mound. The present structure dates from around 3500 BC, apparently replacing an even earlier structure.(A number of engraved stones have been found to have carvings on the reverse side).