Snowdonia National Park.

Stretching across 823 square miles of North Wales, Eryri (Snowdonia) is a high-contrast landscape of jagged peaks, ancient oak woodlands, and 23 miles of coastline. While Yr Wyddfa (Snowdon) serves as the park’s famous vertical centerpiece, the terrain holds more than 90 other mountains and two UNESCO World Heritage Sites, including the dramatic Harlech Castle. This is a region where industry and nature overlap; massive slate quarries sit alongside "Celtic Rainforests" and rare arctic-alpine flora like the Snowdon lily. Beyond the hiking trails and the rack-and-pinion railway, the park is a living cultural landscape where the Welsh language is the primary tongue for some 26,000 residents. It’s as much a hub for modern adventure sports as it is a repository for Arthurian myth.