Eryri is the national park in the north-west of Wales. Yr Wyddfa — Snowdon — is the highest mountain in Wales and the most walked serious peak in the UK. Around it are valleys of slate, oak woods, and a coast of castles. The Welsh language is everyday here, especially in Gwynedd.
You can ride a rack railway up the highest peak in season, walk a path, or ignore the summit entirely and have a better day in a side valley. The third option is underrated.
See
A path you have matched to the forecast
Llanberis is the long steady way up Yr Wyddfa. The horseshoe and the scrambles are a different sport. Know which you are doing.
A slate town
Blaenau Ffestiniog or Bethesda. Quarries made this landscape as much as ice did.
Betws-y-Coed, then leave it
Useful for outdoor shops and a river. The honeypot, not the mountain.
A castle on the coast
Caernarfon or Conwy if you drop to sea level. Edward I’s ring of castles is the medieval politics made visible.