Around the perimeter is a ring-shaped bank and ditch 350 metres across. Within that is a ring of sarsen stones and within that two smaller non-overlapping circles. It was built over several centuries rather than all in one go, more than 4000 years ago, and nobody is quite sure why. Originally there were hundreds of standing stones hereabouts but most were lost or destroyed in the 14th and 17th centuries by superstitious villagers, angry Puritans and housebuilders in search of materials.
Avebury was restored by Alexander Keiller, a Scottish archaeologist and marmalade magnate, who bought up the surrounding land in the 1930s and returned as many stones as possible to an upright position. The National Trust now own the site and, unlike at Stonehenge, it's free to wander among the stones at any time of day. Winter caveat: Some of the stones are roped off at present, for the purposes of erosion control, as are three of the four sections of the outer bank, but this shouldn't detract from your visit.
The Avebury circle is divided into quarters by roads which pass through gaps in the outer henge at approximate compass points. Two are intermittently busy, carrying the main road between Swindon and Devizes, one's a dead end lane and the other leads into the heart of the village. They meet in the vicinity of the Red Lion, a 400 year-old thatched hostelry and the only pub where the landlord pulls pints within a stone circle. Winter caveat: Normally you can walk all the way round the perimeter, exploring each quadrant in turn, but at present the gate closest to the visitor centre is locked. The entire circuit remains accessible.
The outercircle is most obvious in the two western sectors, with any gaps infilled by short pointy pillars. The southern inner circle is more intact than the northern. Some of the stones are massive, indeed one is said to have toppled onto on a barber surgeon in the 14th century and crushed him to death. No stones are balanced on top of other stones - for that you need to be at Stonehenge 17 miles to the south. Winter caveat: The grass is a bit muddy around the stones, there being no paved or gravel paths, but the ground's nothing shoe-destroying at present.
It's quite the place for a good wander (or to walk the dog, if you're a villager). I particularly enjoyed the opportunity to clamber up onto the southeastern bank for a wider view across Avebury and the surrounding countryside. The carpet of gnarled beech roots where the bank dips down to the road is rather splendid. Winter caveat: One joy of visiting in February is that the circle is mostly devoid of humans, so the stones really stand out rather than being lost within a surrounding throng.
As well as the pub and several cottages, the interior of the outer circle also contains a farmhouse, a pillar box, a proper K6 telephone kiosk, two bus stops and four shops. Elements and the Henge Shop are a bit new age, selling spiritual jewellery, handicrafts and other gifts. Cobblestones is a National Trust second hand book depository, so only borderline retail. The fourth is the Avebury Community Shop - a reminder that people actually live here - offering proper groceries including pastries, preserves and handmade flapjacks. Winter caveat: The Henge Shop is a 'wipe your boots before entering' establishment, and mine were already well past that stage. The Community Shop had no such qualms, so that was obviously my favourite.
The National Trust base (and car parks) are located just beyond the circle's rim. Here daytrippers muster to gain their bearings, and return later for a pot of tea. There's also a two-part museum, one small gallery displaying several of Alexander Keiller's archaeological finds and one large thatched barn part-filled with information boards. I over-estimated how long it would take to look round. [NT][EH] Winter caveat: Normally you can also explore Avebury Manor, a National Trust-owned early Tudor manorhouse, but that doesn't open for the season until next weekend.
Various other prehistoric features cluster around Avebury, the closest of which is an undulating corridor of paired stones called the West Kennet Avenue. This stretches for a mile and a half from the edge of Avebury to an even older circle site on Overton Hill, and can be followed all the way on foot. I only made it to the top of the brow before running out of time. Winter caveat: The low sunshine was beautiful but dazzling, which made looking down the length of the avenue a bit squinty. Several of my Avebury photographs didn't come out very well as a result.
The one neolithic monument I really wanted to see was Silbury Hill, a flat-topped cone of earth 39m high and Europe's largest prehistoric man-made mound. No public access is permitted to the hill itself but the A4 runs immediately to the south following the line of a Roman road. From Avebury I had to follow a footpath from the edge of the main car park alongside half a mile of the upper Kennet before the treeline cleared and the hill became visible. Winter caveat: Absolutely nobody else was doing this because the riverside footpath was poorly signed and incorrigibly muddy. The ground stayed just the right side of quagmire throughout but my progress was slow and I realised I was only going to get a photo into the low sun anyway. I made it far enough to go wow, loud enough for nobody to hear, then retreated.
Avebury's easiest to get to if you drive, but I took the number 49 bus out of Swindon for a rollicking half hour ride. Along the way we crossed the M4, climbed steeply onto the downs, spotted a white horse carved into the hillside and passed the hangars used by the Science Museum to store half a million of their undisplayed exhibits. It's not every day you ding the bell and get dropped off inside a stone circle. Winter caveat: My outbound ride was marred by condensation across the upper deck, courtesy of the heavy complement of elderly travellers using their bus passes to travel to Devizes.
And that's how you do Swindon and Avebury in a day.