St Aldhelm's Head Chapel

The wind hits you the moment you reach the top. Ahead, on a flat, treeless headland with the Channel falling away on three sides, sits a squat little building of grey stone, low and square and ancient, hunched against the weather as though it has learned over centuries exactly how to endure it. This is St Aldhelm's Chapel, and it has stood on this exposed clifftop for the better part of nine hundred years.

The chapel was built around the year eleven forty, in the Norman age, and it is a genuine oddity. Most chapels are long rectangles, but this one is almost perfectly square, its heavy vaulted roof carried on a single massive central pillar, so that the interior gathers around that one great stone column. Its exact purpose has never been certain. It may have been a chantry chapel, where prayers were said for the souls of the dead, but perched so prominently above the sea it almost certainly doubled as a seamark, a fixed point that sailors could recognise from far offshore. Faith and navigation, salvation and safe passage, met here in the same small building.

This headland, sometimes called St Alban's Head, has a longer story of watching the sea. In the Second World War it became a centre of pioneering radar research, work that helped defend the coast and the country, and a memorial nearby remembers the scientists and engineers who laboured here. For centuries too the Purbeck cliffs around you were quarried for their fine limestone, hauled up from ledges cut into the rock face.

Let me point out what to look for. First, step inside the chapel itself, out of the wind, and put your hand near that central pillar, the strange squat heart of the building, and let your eyes adjust to the dim, vaulted space. Second, come back out and see how the chapel sits utterly alone against sky and sea, no village, no trees, just stone and grass and the horizon, one of the most atmospheric scenes on the whole coast. Third, find the radar memorial and take a moment over it, thinking of the quiet, unglamorous work that went on here. Fourth, look along the cliffs for the old Purbeck stone quarries, ledges and spoil that tell of centuries of hard labour. And fifth, scan the sea and sky, for this is a fine place to watch guillemots on the ledges, migrating birds passing the point, and sometimes dolphins working the water below.

This is an exposed, strenuous stretch of the Coast Path, and the clifftops here are high and sheer. Keep well back from the edge, especially when the wind is strong, and carry water, for there is little shelter and no shop. If you have come along the range walks from the west, remember to check the published firing days before setting out. The rewards for the effort are wide, uninterrupted views along the Channel and the deep, clean quiet of a headland that has changed little in a thousand years.

Here is the thing to hold in your mind as you stand here. For centuries, sailors beating up or down this coast in every kind of weather would have strained their eyes for this small grey shape on the skyline, this squat chapel that told them exactly where they were on a dangerous shore. It was a prayer and a landmark at once, built by people who understood that the sea gives and the sea takes, and who set a stone on the highest ground to help their neighbours home. It is doing the same for you now.

From here the Coast Path runs on along the great Purbeck cliffs towards Worth Matravers and the final miles, past Corfe's ruined castle inland, out to the white stacks of Old Harry, and at last to journey's end. Take a long look at the sea before you go. Walk safe.