The ancient parish of Llangollen was divided into three parts : Llangollen Traean, Trefor Traean, and Glyn Traean.
Llangollen Traean contained the townships of Bachau, Cysylltau, Llangollen Abad, Llangollen Fawr, Llangollen Fechan, Feifod, Pengwern and Rhisgog.
Trefor Traean contained the townships of Cilmediw, Dinbren, Eglwysegl, Trefor Isaf and Trefor Uchaf.
Glyn Traean contained the townships of Cilcochwyn, Crogen Iddon, Crogen Wladys, Erwallo, Hafodgynfor, Nantygwryd, Pennant and Talygarth.
There has been a church in Llangollen since probably the sixth or seventh centuries. A new building was erected in the thirteenth century; and another, probably in the early sixteenth century, following a fire. The tower was built circa 1750. The church was restored and extended between 1876 and 1883.
As with so many ancient Welsh towns, it takes its name from its founding Saint; Collen, a seventh century saint. Llangollen, was established in the 7th Century when The monk St. Collen was instructed to find a valley by riding a horse for one day and then stop and mark out a "parish" a place to build his hermitage or cell in the custom of the times, with tiny church, hospice and outhouses all enclosed within a wall.
Up to the I9th century Llangollen town was located south-east of the bridge around Bridge Street and Church Street, and to the north-west around the old village green, which has now disappeared, but is remembered by such names as 'Green Lane; and 'Green Lodge' which still exist. Llangollen became important because of its prominent position on the main London to Holyhead coaching road which was improved by Thomas Telford from 1815 and continued for some 15 years. Opened in 1862 the Ruabon to Barmouth railway steamed its way through the Welsh countryside.
The Canal was also constructed around this and combined to bring considerable immigration into Llangollen during the early part of the 19th century.The Canal runs through the Vale of Llangollen and across the world's biggest aqueduct at Trevor. Towering 126 feet above the river and built by Thomas Telford it is a masterpiece of engineering.
These improved communication routes and local natural resources made an ideal location for newly developing industries. The old Water Mill opposite the Railway Station had already functioned for hundreds of years when a new Flannel Mill was erected at the north end of Church Street on a site later to be occupied by a tannery after the business had expanded and moved across the river to Lower Dee Mills.
The large mills of Llangollen were different in character to those in the remainder of Denbighshire, not being a natural development from the earlier pandai or weaving shops, but requiring considerable investment by incoming capitalists, though until the 1860s most of the mills were engaged carding and spinning wool that produced yarn for a large number of domestic weavers in the surrounding districts. George Borrow in the mid 19th century, for example, describes in his Wild Wales how John James, his guide at Llangollen, showed him the path across the mountain along which he used to carry the flannel he wove at home to the mill-owner that employed him.
The partners John Hughes and Edward Roberts took over the Lower Dee Mill in the 1840s, and built another mill, the Upper Dee Mill, in the mid-1850s. On the 1881 census returns for Llangollen, a number of 12 and 13 year olds are listed with occupations such as 'wool spinner', 'factory hand', 'wool picker', and on the 1871 census returns a ten-year-old boy is recorded as a weaver.
Slate in Llangollen
The Llangollen district formed a distinct region of the slate industry in north-east Wales and though small by contrast with the scale of the industry in north-west Wales was significant locally. Quarrying began in the 17th century, though the most intensive period of working came in the 19th and the earlier 20th centuries, following in the wake firstly of the canal and secondly the railway which enabled the slate to be easily exported.
From 1852 the transport of slate from the large Oernant, Moel y Faen, Berwyn quarries was facilitated by the opening of a tramway which skirted the eastern fringes of Llantysilio Mountain to feed the incline at Maesyrychain, within sight of Valle Crucis Abbey. The slate was transferred by this means to a lower tramway which ran to the Pentre Felin Slab and Slate Works sited on the canal just to the north-west of Llangollen.
The extensive open, hilltop workings with some underground workings at Moel-y-faen were mainly developed following connection to canal by an extension of the Oernant tramway in 1857. The hillside workings at Craig y Glan on the northern edge of Llantysilo Mountain operated in 1870–80s.
The Pentrefelin slate works, dating from the 1840s, lay on the canal wharf and were later provided with a railway loading point. The mill was powered by a waterwheel driven by the canal itself and handled material brought from the Horseshoe Pass quarries by the Oernant tramway.