Bakewell is the largest settlement and only town in the national park and the site of the National Park Authority offices. Its five-arched bridge over the River Wye dates from the 13th century. Castleton is the centre of production of a semi-precious mineral, Blue John. Eyam village is known for a self-imposed quarantine during the Black Death. Edale is the southern end of the Pennine Way, a 268-mile national trail which traverses most of the Pennines and ends at Kirk Yetholm in the Scottish border. Other villages in the park include Flash, Hathersage, Hartington, Ilam and Tideswell.