Why the islands hold the oldest stones

Britain's coasts and islands carry a disproportionate share of our earliest monuments. There are practical reasons for that. Glacial drift left boulders scattered across the landscape, thin soils made ploughing difficult, and anyone wanting to raise a statement in stone rarely had to look far for raw material. But there is a deeper logic too. Five thousand years ago the sea was a highway, not a barrier, and communities around the Irish Sea, the Hebrides and the Northern Isles were in regular contact. Standing stones, chambered cairns and cliff-edge forts were the shared grammar of a seafaring world, and island settings have preserved them far better than the intensively farmed English lowlands.

What follows is a rough circuit of the best of it, with a few practical notes for anyone planning to travel out to see them.

Orkney: the Neolithic heartland

Nowhere in the UK packs so much into so small an area. On the narrow neck of land between Lochs Harray and Stenness you can walk from the Stones of Stenness, a handful of towering slabs in a henge bank, across to the Ring of Brodgar, a great circle of around two dozen surviving stones set in a ditch cut from solid rock. The walk between them takes about twenty minutes.

Nearby, Maeshowe is a chambered tomb aligned so that the setting midwinter sun shines straight down its entrance passage. Book ahead if you want to go inside, and if you can, go in December or January when the light does its work. Skara Brae, Europe's best-preserved Neolithic village, sits above the beach at the Bay of Skaill, its stone dressers and hearths still intact after five millennia. Add the stalled cairns at Unstan and Cuween Hill, and the settlement at Barnhouse, and you have a long weekend's worth of archaeology within a few miles.

The Atlantic islands: Lewis, Harris and the Uists

Calanais, on the west coast of Lewis, is the most complete of the great stone settings: a central monolith almost five metres tall, ringed by thirteen stones, with avenues running out to the north. The local gneiss is among the oldest rock in Europe, and the whole complex glitters with quartz when wet. Most visitors stop at the main circle and miss Callanish II, III, IV and the rest, which are scattered across the moor within walking distance.

Carry on to North Uist for Barpa Langass, a chambered cairn on the hillside above Loch Langais; its roof has partly collapsed, and you can peer into a chamber built before the pyramids. On Lewis, Dun Carloway is one of the finest brochs anywhere, a drystone tower of the Iron Age with a wall still standing several metres high. The Outer Hebrides reward a slow pace: hire a car, accept that single-track roads mean constant passing places, and give yourself a full day per island.

Anglesey, Man, Cornwall and Scilly

Closer to the main road network, the Irish Sea coast is just as rich. On Anglesey, Bryn Celli Ddu is a passage tomb where the rising sun at midsummer shines down the passage to the chamber, and the coastal tomb of Barclodiad y Gawres sits above a rocky bay with carved patterns on its stones. On the Isle of Man, Meayll Hill above Port Erin has six burial chambers set in a ring, cut into the turf in a pattern that looks oddly like a kite.

In Cornwall, Chun Quoit stands on the moorland edge near Morvah with views out to the Atlantic, while the Merry Maidens and Mên-an-Tol are easy to reach from the coast road. On the Isles of Scilly, the entrance graves at Bant's Carn and Innisidgen on St Mary's are short walks from the coastal path, and low tide exposes prehistoric field walls between the islands.

Iron Age forts on the edge of the sea

The later prehistoric period took full advantage of coastal topography. Dun Aonghasa on Inishmore in the Aran Islands is the most dramatic: a semicircular stone fort perched on a cliff edge, defended by bands of sharpened upright stones known as a chevaux de frise. Similar promontory forts punctuate the Cornish coast at the Rumps and Trevelgue Head, and the Welsh and Pembrokeshire headlands.

Where the sea itself provided the defence, access is often across a tidal causeway or a narrow neck of land. Plan your visit around the tide, not the other way round.

Practicalities for island stone-hunting

• Tides first, timetables second. Causeways to places such as the Brough of Birsay in Orkney are covered at high water. Check a local tide table, not an app for a different harbour, and allow a generous margin.
• Ferries run on island time. Winter and shoulder-season sailings can be cancelled at short notice, so keep the last day of a trip loose and never book a same-day connection off an island.
• Light and season. Low winter sun rakes across carved surfaces and shows up the cup marks you would otherwise miss. Midges on the west coast and Hebrides peak from June to August; take repellent or travel in May and September.
• Ground conditions. Many sites sit on rough moorland or in working farmland. Wear boots with grip, close every gate, keep dogs on a lead near livestock, and follow waymarked paths rather than cutting across pasture.
• Respect the monument. Don't climb on cairns, light fires, move stones or leave offerings. Most of these sites are legally protected scheduled monuments, and unauthorised metal detecting on them is a criminal offence.
• What to read before you go. A large-scale map of the area is worth more than any guidebook, since many of the finest smaller stones and cairns are unmarked on the ground.

Go quietly, go slowly, and you will find that these places still do exactly what they were built for: marking time, holding territory, and keeping a community in step with the turning year.