stylistic:tone, structural:reformatting
Umbria-Marche Apennines

The west border of the Umbria-Marche Apennines (or Appennino umbro-marchigiano)) runs through Cagli. They extend south to the Tronto River, the south border of the ONA.The highest peak, Monte Vettore, at 2,478 m (8,130 ft), is part of the Monti Sibillini, incorporated into Parco Nazionale dei Monti Sibillini. Further north is the parco naturale regionale della Gola della Rossa e di Frasassi, in which are the Gola della Rossa ("Red Gorge") and Frasassi Caves. Still further north is Parco Sasso Simone e Simoncello. The Italian Park Service calls it the "green heart" of Italy. The region is heavily forested, such as the Riserva Naturale Statale Gola del Furlo, where Furlo Pass on the Via Flaminia is located. Both the Etruscans and the Romans constructed tunnels here.