On the summit sits a circular bank about 250 feet across, surrounded by a ditch. The defensive logic falls apart on inspection. The outer wall is too low to have stopped anything; archaeologists have ruled out hillfort as a primary function. The alternatives are stranger. Some have suggested a Plen an Gwarry, the type of Cornish amphitheatre with stone seating where mystery plays were staged and feast days celebrated. Others see a large disc barrow, an unusually elaborate ceremonial burial mound. Still others lean toward sacred enclosure, a space marked off from ordinary ground for ritual use. In the centre, three smaller stone circles once stood in a triangle, the largest forty feet across. The stones are gone, taken for walls and gateposts by farmers who saw a quarry where their ancestors saw a temple.

Bartinney was a site of the Celtic fire festivals. Parish records and antiquarian accounts describe ceremonies marking the harvest and Samhain, the Celtic New Year on the eve of November 1. The Druids, the tradition holds, kept a sacred fire burning here, and on those nights every household in the surrounding farms had to extinguish its hearth and walk up the hill to relight from the consecrated flame. The discipline was theological as much as practical. To carry fire home from Bartinney was to bring the year itself back inside, kindled fresh from a source the community trusted. The god honoured here, by local tradition, was Belenos, the bright one, the Celtic solar deity whose name still echoes in Beltane.

The strangest thing about Bartinney is how slowly the old practices faded. Nineteenth-century accounts describe Midsummer's Day in this parish as a riot of noise and fire. The villagers bored holes in the granite outcrops, packed them with gunpowder, and detonated them in sequence so that the whole peninsula echoed like musket fire. Every working tin mine flew a new flag. As darkness fell, bonfires blazed on every hill. The Christians had been preaching in Cornwall for thirteen hundred years by then, and still the people climbed up to the high places on the longest day and the night the dead returned, and they lit the fires their ancestors had lit. The form of worship changed; the rhythm beneath it did not.

There is a final layer of meaning in the name. Tinne, in the Druidic ogham tree alphabet, is the holly, whose burning marked the dying of the old year and the kindling of the new at Samhain. Tinne, in the same texts, also means a metal ingot or an iron bar. Bartinney sits in the middle of the richest tin and copper country in prehistoric Europe. The Iron Age people who came to this hill came carrying metal from the workings on Carn Brea and Carnyorth, and they burned holly on a hill named for both. Modern visitors find a trig point planted in the centre of the enclosure and a panorama that takes in the whole tip of Cornwall. The fires are out. The ditches remain.