Cerrigydrudion, sometimes spelt Cerrig-y-drudion, is a village and community in Conwy, Wales. Until 1974 it was part of the historic county Denbighshire, when it became part of the newly formed county of Clwyd. When the county of Clwyd was abolished in 1996, the village was transferred to the new Conwy County Borough. The village formerly lay on the A5, but a short by-pass now takes the road along the south-western edge of the village. Prior to the by-pass being built, Cerrigydrudion was the highest village on the A5 between London and Holyhead. The community includes the hamlets of Cefn Brith, Glasfryn and Pentre-Llyn-Cymmer with the village having a population of around 289. The community is sparsely populated and covers over 60 square kilometres.

Llyn Brenig is a reservoir located on Denbigh Moors in North Wales. The artificial lake, which was constructed between 1973 and 1976, was created by building an embankment dam across the Afon Brenig valley. It lies at 1,200 ft (370 m) above sea level on the border between the counties of Conwy and Denbighshire. It is used to manage the flow in the River Dee as part of the River Dee regulation system.