Yes we can be sure that Neolithic monuments such as Newgrange in the Boyne Valley in County Meath and Maes Howe on Orkney were constructed to have a special meaning at the winter solstice/shorest day.

The architects and engineers of the amazing monuments were fully aware of the cycles of the earth and the heavens and they designed according to what was important to them.
Newgrange and Maes Howe are monuments of advanced construction techniques. They are places where the dead were buried but also were the living visited and bestowed symbolism and meaning. As the sun rises on the shortest day ( and a few other days around that date) the sun streams into the burial chambers and along the passage ways lighting them. When the original burials were in place the remains of the dead would be illuminated within the chambers. This event must have had enormous symbolism and meaning for the community and great ceromony may have surrounded the event.
Up to 30,000 people apply to visit Newgrange at this time each year.