At first it was a small smudge in the top left hand corner of the horizon, grey against paler grey. Shallow grasslands rolled round us, speckled with sheep. A kestrel hovered and dropped. It was only as we breasted the last hill that the smudge resolved itself into the familiar stone jack’o’lantern grin, known across the world as one of Neolithic man’s most startling achievements: Stonehenge.I’d never seen it like this, in perfect isolation, exactly as people would have seen it over 4,000 years ago when they trekked up the wide processional route known as The Avenue, which approaches the stone circle from the northeast. I wish I could be there just before four o’clock on Saturday, the evening of the winter solstice, to see the sun set for the last time on the hideous bunker of the old visitor centre.