The first and second ramparts are still distinct on the ground, overgrown now with trees on the north and east sides but recognizable as circular banks of earth and stone rubble. The third is fragmentary, easier to trace in winter when the bracken dies back. The fourth is the ghost: visible mainly from the air or on those old OS maps, an incomplete D-shape running west and south down the slope. Two entrances cut through the eastern and northern sides, opposite where the outermost wall extends, suggesting the builders wanted defenders to face outward toward open ground rather than toward the steepest slopes. There is no dressed stone. The palisade and any internal buildings were wooden and have rotted away entirely. Archaeologists classify Prideaux as a small multivallate hillfort because the enclosed area is less than one hectare. That puts it in a known category but tells us almost nothing about what really happened on this hill.

Prideaux did not stand alone. It guarded a stretch of what later became known as the Saints' Way, the ancient trade route that crossed Cornwall from the Fowey estuary to the north coast at Padstow. For travelers and traders heading inland with cargo, the hill would have been a landmark before it became a fortification. Tin from these hills moved along this route as far as the Levant during the Bronze Age, and Cornwall's tin was an essential ingredient in bronze across the ancient Mediterranean. The Iron Age people who built Prideaux inherited a landscape already organized around metal trade. The economy continued through Roman times and into the medieval period, when the same area became known as Pridias, one of the eight tithings of the Blackmoor Stannary chartered by King John in 1201. The same crown of hills that held the hillfort still held the tin records, stored at the church in Luxulyan.

Eighteenth-century antiquaries could not resist the French look of Prideaux. Thomas Tonkin derived the name from près d'eaux, near the waters, despite the obvious problem that the hillfort sits at 135 metres on a dry summit several kilometres from the sea. The truth is more Cornish than French. The earliest documented forms suggest something like bredinas, from bre meaning hill and dinas meaning castle or fort. Hill-fort, in other words. The French spelling Prideaux only appeared during the Plantagenet centuries, when Norman scribes wrote everything as if they were still in Rouen. The hill itself became more than the fort. Three nearby hamlets on the 1888 map were called Prideaux, Little Prideaux, and Great Prideaux, a family of place names spreading down the slope from the unnamed summit where the rings still curl.

The honest answer is that no one knows. Excavated hillforts often reveal hut circles, kilns, or storage pits that hint at long-term habitation. Prideaux has none, or at least none yet found. Cornish cliff castles and hillforts of this size were sometimes used as seasonal gathering places, ceremonial sites, or refuges in times of trouble, rather than year-round towns. Some served as visible markers of power, designed to impress observers from the landward side as much as defend against attackers. The fact that Prideaux's outermost wall extended only on the downhill slopes, where it would be most visible from below, suggests the builders cared about how the fort looked as much as how it fought. After the Iron Age there is no evidence of any subsequent structure on the hill. The Domesday Book of 1086 makes no mention of either Luxulyan or Prideaux, although nearby Tywardreath shows up as held by Robert, Count of Mortain. The conical summit was left to weather quietly, ringed by walls that had outlived the people who built them.