This is the largest of the North Wales copper mines where mining appears to have been carried out over a long period though the visible remains date largely from the eighteenth century onwards. The site is dominated by two large opencast pits (the Parys (NPRN 300166) and Mona (NPRN 300167) pits) created initially through the collapse of underground workings accessed by shafts and levels. These pits, however, represent only a small proportion of the total workings. Shafts to extant underground tunnels have been capped. The windmill (NPRN 306041) on the summit and the Cornish engine house (NPRN 33670) are well-known landmarks though the commonest visible feature remaining (aside from spoil tips) are precipitation pits (e.g. NPRN 33753). Other structures visible on the mountain include the Mona mine yard, remains of cobbing floors, reservoirs, leats, whimseys and engine houses.
Copper ingots with Roman inscriptions have long been known from the vicinity of Parys Mountain, and a Carbon14 date from charcoal from the excavation of a spoil tip (in the 1980s) has led to claims for an Early Bronze Age origin for these workings.

D.K.Leighton, RCAHMW, 8 September 2004.

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The technicolour moonscape on Parys Mountain gives evidence of the once booming, and world famous, copper mines of Anglesey. Although archaeological evidence shows that copper was extracted from Parys Mountain as early as the Bronze Age, large-scale industrial production only developed after the discovery of a particularly rich lode in 1768. Developed by Thomas Williams, the country's first `Copper King?, by the 1780s the Parys Mountain Copper Mines, owned by Nicholas Bayley, MP for Anglesey, were the largest in the world. The copper ores were shipped from the port of nearby Amlwch to Swansea, then the global centre of copper smelting, and found particular fame when they were used to sheath the hulls of Nelson's naval ships.

Many foreign visitors came to see the famed copper mines of Parys Mountain to study open cast mining and the preparatory smelting procedures as well as marvel at the large mining pits and brightly coloured slag heaps. In 1796, the young Austrian count Gottfried Wenzel von Purgstall toured the whole of Wales and made a stop here. Describing himself as a layman who did not understand much of the technical aspects of smelting, his account gives a good impression of the mines at their peak of production. At a similar date, August Gottfried Lentin spent a few weeks in north Wales with the intent to study the open cast mining at Parys Mountain in greater detail. To this date, his series of letters count among the best contemporary descriptions of copper mining, its related industries, and the environmental and social impact on the people and isle of Anglesey.

Although the industry declined rapidly in the early nineteenth century, the impact of copper mining on Parys Mountain is still visible today with brightly coloured broken ground and the ruins of industrial structures scattered across the area. Despite the ongoing struggle against the pollution of the soil and water, some rare plants continue to grow. Local guides now offer tours through the historical open cast pits and mining levels.

Record updated as part of the AHRC-funded project 'Journey to the Past: Wales in historic travel writing from France and Germany'.
R. Singer (Bangor University) and S. Fielding (RCAHMW), 2017.