Llangollen is a small town in Denbighshire, north-east Wales, situated on the River Dee and on the edge of the Berwyn mountains.
Llangollen takes its name from Saint Collen, a 7th century monk who founded a church besides the river here. St Collen is said to have arrived in Llangollen by coracle. As there are no other churches in Wales dedicated to St. Collen, it is possible that this St. Collen may also have connections in both St. Collen, Cornwall and Langolen, Brittany.
Standing high above the town to the north is Castell Dinas Bran, the former stronghold of the Princes of Powys. Beyond the castle is the limestone escarpment known as the Eglwyseg Rocks. The outcrop continues north to the area known as World's End. The area nearest to the castle is known as the Panorama Walk, and a monument to local poet I.D. Hooson (from the nearby village of Rhosllanerchrugog) can be found there.
Valle Crucis Abbey was established in nearby Llangwestl in about 1201, under the patronage of Madog ap Gruffydd Maelor of Castell Dinas Brân.
The famous bridge at Llangollen was built in about 1345 by John Trevor, of nearby Trevor Hall, who later became Bishop of St Asaph.
On the outskirts of the town is Plas Newydd ("New Place" or "New Hall"), where The Honourable Sarah Ponsonby and Lady Eleanor Butler (the Ladies of Llangollen) lived.
The ancient parish of Llangollen was divided into three treanau ("trean" being the Welsh for "third"): 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, Crogeniddon, Crogenwladus, Erwallo, Hafodgynfor, Nantygwryd, Pennant and Talygarth.