IRELAND // If you're talking about significant mounds of rock, England's Stonehenge comes with a certain historical fame, but Ireland's Brú na Bóinne has the clout of a thousand extra years. It's an extraordinary sight and a testament to the mind-boggling achievements of our prehistoric ancestors: an enormous Neolithic necropolis of squat, rotund tombs set in emerald plains. The pick of the monuments is Newgrange, with its futuristic white stone walls and grass dome above a prehistoric passage tomb. Steeped in Celtic mythology, the purpose of the site is something of a mystery, though it's believed to have been a burial place for kings. At the winter solstice, the rising sun's rays shine through the opening above the tomb's entrance, illuminating the chamber in what is one of the country's most memorable experiences.