Monuments, imposed on landscapes all over the world, represent human progress, civilisation and community - think of Egypt's pyramids; the Nazca lines of Peru; Spaghetti Junction. Britain's first monuments - stone circles, lines and cairns - are almost 5,000 years old and chart our ancestors' passage from the Stone Age to the Bronze Age. Many still stand and provide a fascinating link to our pre-Christian heritage.
Pagan religion was at the heart of Stone Age society and the source of its most dramatic monuments. Stone circles were open-air temples and the locations for frequent ceremonies. One of the best remaining circles is Avebury, Wiltshire (on the A4361, tel: 01672 539 250). The circular ditch, a quarter of a mile in diameter, was dug with deer-antler pickaxes. It was 27ft deep in places and the earth was scooped up with ox shoulderblades.
Silbury Hill nearby, beside the A4 between Marlborough and Beckhampton, was the largest and most important altar in the country, standing 130ft tall. Pilgrims would have approached along the Ridgeway, so that the top of Silbury would appear to float along the horizon beside them. Its construction was a feat of engineering - a pyramid was formed by colossal blocks of chalk then filled with chalk rubble to make the white hill.
The Druids' Circle, above Penmaenmawr (you'll need OS map 115.723746) is a complex of about 30 granite stones overlooking Tal y Fan and Colwyn Bay. It is a steep climb, but worth the effort. The Stone of Sacrifice has a cavity large enough for a young child: legend has it that any child placed in the hollow in the first month of its life would be lucky in adulthood.
However, the circle was excavated in 1958 and two child burial sites were discovered (one with a bronze knife and three sandstone sharpeners). Obviously some children were not as fortunate as others.
Possibly the most important circle, the Rollright Stones, stands alone on an ancient Cotswold ridgeway (take the A3400 out of Long Compton, the second right takes you past the stones). They are known locally as the Kings' Men, who were turned to stone by a witch (the King himself is the large stone outside the circle). Their original intention is not clear and subsequent generations have created their own myths - but ask children to try counting them and they will always end up with different totals.
The 35 stones of Castlerigg, which are about 4,500 years old, are ringed by breathtaking Cumbrian mountains: Skiddaw, Lonscale Fell, Blencathra and Clough Head and it was here that a large stone axe was found. They are signposted out of Keswick town centre to the west, between the A66 and the A591.
Tal y Fan mountainside, between Dolgarrog and Conway in North Wales, is scattered with monuments, including the poet stone and Maen-y-Bardd. Whoever spends the night beneath it will either go mad or become a poet.
Many sacred circles were approached along lines of stones. The long rows at Merrivale, Devon, have been known as the Plague Market since the seventeenth century, when the healthy would bring food to plague victims out on the moor: from Tavistock take the B3357 to Merrivale, pass through the village and you'll find the stones on a plateau on the other side.
Many burial mounds are similarly preserved. Belas Knap, in the Cotswolds between Winchcombe and Cheltenham, is a 200ft longbarrow. Inside there are four polygonal burial chambers accessed through a secret entrance and passageways inside the mound. Excavations in 1863 and 1928 unearthed the remains of almost 40 people, as well as a boar tusk pendant and stone implements which are now in Cheltenham Art Gallery & Museum (01242 237 431).
King Arthur's Hall, an open rectangular earthwork on the western edge of Bodmin Moor in Devon, and only one of many monuments tenuously linked to Arthur, is within walking distance of four stone circles. Also on Bodmin is a network of three stone circles, The Hurlers. The most famous of the Arthur series, Arthur's Stone, has a huge 25-ton capstone which suggests it was an important tomb, although it is possibly the world's heaviest picnic table these days. It can be found near Hay-on-Wye on the road from Bredwardine to Dorstone.
The Stone Age, so-called because of the flints that were essential for agriculture, witnessed the first settlements of Britons. As hunters began using the stars to navigate by, societies became less nomadic. This allowed people the freedom to farm and the Stone Age slowly became the Bronze Age. Weapons evolved and became more lethal so communities were not so eager to fight among themselves. Beyond this burgeoning civilisation, however, continental Europe was as controversial a problem for Ancient Britain as it is now. Roman writers, precursors of tabloid journalists, dwelt on the British druids' human sacrifices. Consequently when the Roman army first landed in Kent in AD43 they expected to encounter barbarians.
Rome's greatest fear was that the Britons would export their pugnacious attitude to the Gauls of northern France. But gradually Roman armies subjugated British kingdoms. Resistance fighters were corralled first in Wales with the construction of the Fosse Way and then in the druids' nerve centre, Anglesey. They built Roman roads close to many monuments, such as Stonehenge and Silbury, to keep a close eye on these potential hotbeds of British dissent.
However, they did not completely destroy the sites and many retain an aura of mystery. Why, for instance, was the Uffington White Horse, in Oxfordshire, built? The area has attracted pilgrims for centuries and is believed to date from the early Bronze Age. It overlooks a conical hill called Dragon Hill where St George is supposed to have slain the Dragon. Both are clearly visible from the B4507 between Woolstone and Kingstone Lisle.
The Long Man of Wilmington , emblazoned on the side of Windover Hill in Sussex, is equally puzzling, although the image has been found on a fourth-century coin and a Saxon belt buckle. He is one of only two human hill carvings (the other is the Cerne Abbas Giant in Dorset).
But undoubtedly the most extraordinary site, Callanish, requires an excursion - to the Outer Hebrides and the island of Lewis.
Essential kit: Ordnance Survey maps, walking boots and the indispensable 'The Modern Antiquarian' by Julian Cope (Thorsons, £29.99)