St Michael's Mount

Out in the bay before you rises an island crowned by a castle. When the tide is low, a cobbled causeway leads across the sand to its foot; when the sea comes in, the water covers the path and the island stands alone, reached only by boat. This is St Michael's Mount, one of the great landmarks of Cornwall, a medieval castle and church on a granite peak in Mount's Bay, with a harbour village at its base and subtropical gardens clinging to its slopes.

The Mount has been a holy place for at least a thousand years, an early Christian and perhaps far older sacred site, a landmark for pilgrims and a beacon for sailors making the bay. In the twelfth century a Benedictine priory was founded here, granted to the great abbey of Mont-Saint-Michel in Normandy, whose island silhouette this one so closely echoes across the Channel; the two rocks, one Cornish and one Norman, have been twins in the imagination ever since. After the monasteries were dissolved, the Mount passed through many hands until, in 1659, it was bought by the St Aubyn family, whose descendants live in the castle still. In 1954 the family gave the Mount to the National Trust while keeping a long lease, so it is now cared for jointly, home and monument at once. The mild Gulf Stream climate lets exotic plants flourish in its terraced gardens, clinging improbably to the seaward rock, and seals are often seen out in the bay.

From the mainland at Marazion, look for several things in turn. First, the castle and church on the summit, medieval stone rising straight from the rock, the whole island a single dramatic silhouette. Second, the causeway itself, a natural ridge of granite boulders that surfaces only at low tide; watch how it appears and vanishes with the sea, and note the little harbour and cluster of village houses at the island's foot. Third, look at the water of Mount's Bay all around, and out to the low submerged forest remains sometimes glimpsed on the sands, hinting at a drowned landscape from when the sea was lower. Fourth, scan the bay for wildlife: seabirds and waders along the shore, and seals surfacing offshore. And fifth, if you cross and climb, look back from the summit for a sweeping view over the whole of Mount's Bay. Above all, check the causeway tide times before you set out, so the sea does not strand you, and take care on the steep, wet cobbles.

For a tale to carry with you, the Cornish tell of a giant. His name was Cormoran, and long ago, they say, he lived upon the Mount and terrorised the mainland, wading ashore to seize cattle and carry them back to his island lair. No one dared face him, until a bold local boy called Jack rowed out one night, dug a great pit on the hillside, covered it over, and at dawn blew a horn to wake the giant, who came blundering down and tumbled straight into the trap. For that deed Jack was known ever after as Jack the Giant Killer, and this island in the bay is where the very first of those famous giant-killing tales is said to have begun.

From Marazion the South West Coast Path runs on around the shore of the bay towards Penzance and Newlyn, the Mount always at your shoulder, changing with the light and the tide. Pause once more before you go, and watch the sea decide whether the island shall be joined to the land or set apart from it. Few places on this whole coast change their nature so completely, twice a day, as this castle on its rock. Walk safe.