This short walk, at the edge of Dunnet village, reveals the remarkable history of Caithness' once thriving flagstone industry. The durable grey flagstones had been used for centuries as a building material but their quality became of worldwide interest after a commercial operation began in the 1820s. Castlehill was at the hub of production which at its height, in 1902, produced 35,363 tonnes of flag, valued at £23,239 – an enormous sum in those days. One of the trail’s features is a derelict windmill (pictured) which was ingeniously used to pump water which powered the saws.