Gwynedd was a historic administrative county of north-west Wales, created in 1974 by combining the ancient counties of Caernarfonshire, Merionethshire and Anglesey together with a small part of Denbighshire, and named after the medieval Kingdom of Gwynedd, the most powerful and enduring of all the native Welsh kingdoms, whose rulers, including Llywelyn the Great and Llywelyn ap Gruffudd, the last independent Prince of Wales, had once governed much of this same mountainous territory before its conquest by Edward I in the late thirteenth century. Caernarfon, seat of Edward's own great castle, served fittingly as the administrative county town of this modern revival.
Gwynedd's territory took in the great mass of Snowdonia, including Snowdon itself, the highest peak in Wales and England, giving the county an outsized importance in Welsh tourism, hillwalking and mountaineering, while the Llŷn Peninsula and the island of Anglesey preserved some of the strongest concentrations of Welsh-speaking communities anywhere in Wales, the language remaining the majority tongue of everyday life across much of the county throughout its existence. Slate quarrying, centred on Blaenau Ffestiniog, Bethesda and the Llanberis area, had by the nineteenth century made this corner of Wales the world's leading source of roofing slate, an industry whose vast quarry landscapes are now recognised as a UNESCO World Heritage Site.
When Welsh local government was reorganised in 1996, the name Gwynedd was retained for a smaller successor unitary authority covering Caernarfonshire, Merionethshire and part of the old administrative county, while Anglesey was given its own separate unitary council, a partial but significant continuation of the 1974 county's identity and name into the present day.