Porth Wen means White Bay - the name probably comes from the pale quartzite cliffs above the cove. The brickworks sits on the western side of the bay, in the community of Llanbadrig, 2 kilometres west of Porth Llechog and 3 kilometres north-east of Cemaes. Charles E Tidy built the works in the mid-nineteenth century to exploit the quartzite outcropping just above the cliff. Crushed and mixed with lime, quartzite makes silica fire bricks - the material that lines the inside of steel-making furnaces, where ordinary brick would simply melt. The Victorian iron and steel industry needed enormous quantities, and a coastal site like Porth Wen meant the bricks could be loaded directly onto ships. The works expanded through the late nineteenth and early twentieth centuries; most of the surviving buildings date from the major rebuild around 1900. The site lies within the Anglesey Area of Outstanding Natural Beauty - a protected coast since 1967, by then long after the works had stopped.

The brickmaking process began at two quarries on the cliff above the works. Stone was cut, broken to portable size, and lowered to the works by an incline tramway. The winding house at the top of the incline held two lateral stone walls supporting a square drive shaft on bearings. Three wheels turned on the shaft - one a banding brake about 2 metres across, two driving wheels at 1.5 metres - and a wooden control beam still survives in front of the drive shaft. The incline was gravity-powered: loaded trucks descending pulled empty ones up by means of the cable wound on the drum. Below the incline, the quartzite was fed into the crushing house where a knapping machine smashed it into smaller pieces. The fragments were chuted down to lower levels for further reduction, in part by hand - the workers wearing iron-covered gloves to hammer the stone into fine powder. The powder was mixed with lime and water in a pan mill, then moulded into bricks in the moulding shed.

The shaped bricks dried in the drying sheds, then went into one of the three circular down-draught kilns. Down-draught kilns - sometimes called beehive or Newcastle kilns - are domed structures that pull the heat down through the stacked bricks before drawing it up the chimney, which gives a more even fire than older up-draught designs. The kilns at Porth Wen still stand essentially complete, made of brick with iron banding holding the domes against the outward pressure of the firing temperatures. Each kiln could fire several thousand bricks in a single load over four or five days. Once fired, the bricks went into the warehouse, then out to ships at the quay. A small engine house contained the steam engine that drove the works; the boiler house held the Stirling boiler. By the late 1920s production had ended. The buildings simply stayed where they were.

Cadw designated Porth Wen Brickworks a scheduled monument in 1986, classifying it as a post-medieval industrial brickworks. The Anglesey Coastal Path passes the site, though reaching the ruins themselves requires a careful scramble down the cliff path - there is no official access route, and the National Trust and Cadw both note the structures are in a delicate state. Coastal erosion has already destroyed parts of the quay and lower buildings; the long-term future of the site depends on the rate at which the sea eats the cliff. Photographers and industrial archaeologists make the pilgrimage anyway. The kilns and the chimney, set against the white quartzite cliffs and the green sea, have appeared in countless coffee-table books of British ruins. There is something specific about Porth Wen - the completeness of the surviving equipment, the remote setting, the fact that you have to work to reach it - that has made it one of the iconic industrial ruins of the United Kingdom.