Marche is the Italy that most international travellers have yet to discover. The Sibillini Mountains: part of the Apennine spine: offer some of central Italy’s finest high-altitude walking, including the Piano Grande plateau at Castelluccio, famous for its spring wildflower bloom. To the east, the Adriatic coast stretches for miles, largely crowd-free. In between: Urbino, one of Italy’s greatest Renaissance cities; Ascoli Piceno, a town built entirely of travertine; the Frasassi Caves, among the largest cave systems in Europe.