There is a hollow in the fields to the north of Stonehenge where time stops. As sheep trot away from the intruder, their baas are barely interrupted by the distant rumble of traffic. On the crest of the slope that rises before you, the stones are black against the bright sky. You can't see people around them from this angle. Their setting is such that, behind them, the earth seems to vanish. Stonehenge: gateway to the infinite.
It is no accident that such a perfect view of Stonehenge rewards the walker at this spot. Where you're standing is in fact a turning point on an ancient route, formally marked out by earth banks, that seems to have been the sacred approach to the standing stone circle on Salisbury Plain. It has been called the Avenue since it was first noticed by 18th-century antiquarians. In spring it's almost impossible to see the lines of the Avenue in the new-grown green, but in a winter frost, the course of the ancient earthwork is far more visible.
At this point at the bottom of the prominence known as King Barrow Ridge, pilgrims in the Neolithic age would have turned to face Stonehenge and their hearts might have filled with awe at the final approach towards the most ambitious architectural structure in the northern Europe of their day. Despite all the modern mismanagement of Stonehenge - the roads, the car park, the shabby visitor centre far too close to the ruins - just by going for a walk near the ruins you can still experience something of this ancient wonder.
A walk in the vicinity of Stonehenge, like the 11km circuit you'll find overleaf, is not just a nice stroll in the country with a stone circle as backdrop. It's the best way to appreciate the mystery of Britain's greatest monument. By walking these largely National Trust-managed fields, studded with enigmatic barrows - earthen mounds containing tombs - of various shapes and sizes, arranged in eerie, crop circle-like patterns, you get a deeper and more evocative glimpse of the world that created Stonehenge than you do by a quick visit to the megalithic structure.
Companions ancient and modern can illuminate your walk. William Stukeley was an 18th-century visionary - or nutcase, depending on your point of view - who first created the modern myth that Stonehenge is a temple of the druids where human sacrifice was performed. In reality, it was built in different stages between about 3000BC and 1600BC. The druids emerged at least a thousand years after its latest construction phase. Stonehenge is the creation of remote and elusive people of the late stone age and the bronze age. They left no literary records, so everything that is known of Stonehenge is known through archaeology, the study of physical remains in their context. By walking near Stonehenge you can play at being an archaeologist for a day (but don't take that too literally ... no shovels please).
Eccentric as he was, Stukeley was a great observer of the British landscape. He marked out the course of the barely visible Avenue and, to its north and west, noticed an incredibly long, narrow earthwork arena named the Cursus. Walk along the low, fragmentary traces of this structure and you encounter some of the weird barrows that constellate around Stonehenge. The Cursus barrows are circular mounds arranged in a line parallel to the earthwork. It's quite eerie standing beside them in the long grass. Follow the Cursus still further, to its western end, and you find a solitary, regal-seeming barrow where it's easy to imagine a powerful chief lies interred.
More than two centuries on from Stukeley's haunting engravings of this landscape, it is among the barrows and earthworks of these fields that many modern archaeologists seek the meaning of Stonehenge, and as you walk the fields it becomes powerfully apparent that ancient people didn't just plonk a stone circle here for no reason. The Cursus earthwork - whose purpose is a total mystery - is older than the stones, suggesting this was already an important place. As Stonehenge developed, so did its surroundings. The many barrows where people were buried bear witness to its sacredness.
The one thing you must do when you visit is get close to Stonehenge itself. Perhaps the most amazing fact about Stonehenge is that the lintels on top of its great circle were placed perfectly level even through the ground below is sloping. It must have been done with a plumb line and it was done superbly. This is a work of precision engineering. The very latest archaeological work at Stonehenge - a major new dig last year and a computer analysis of the structure's intricate geometry by archaeologist Anthony Johnson - seems to be opening exciting new lines of interpretation. Is Stonehenge essentially a shrine for the exotic "bluestones" brought as healing relics from the Preseli mountains in west Wales? Is its intricate geometry proof that its makers had trade links with the contemporary Mediterranean world?
Down in the hollow among the dandelions, so close to the car park yet so far from the modern world, the sheep aren't saying.
• Jonathan Jones walked route 4755 (Historic Stonehenge), a "moderate" 11km. For step-by-step instructions and local attractions, see here
