On the 21st of December 1967, Prof. Michael J. O'Kelly became the first person, perhaps in thousands of years, to witness the dawn light filling the chamber at Newgrange on the Winter Solstice.
O'Kelly spent 14 years excavating this incredible site along with his wife Claire.
Entrance to the tomb on the morning of the Winter Solstice is now by lottery, but a livestream of the event allows people all over the world to revel in the 5,200 year old feat of astronomical engineering.
Image from newgrange.com