The Apennines are by definition system mountainous with a length of about 1,200 kilometers, crossing the Italian peninsula from top to bottom, creating an arc with the convex part to the west. The northern end will come to fill the Colle di Cadibona, while in the southern part is the tip dell'Aspromonte, just before the Strait of Messina in Calabria. The highest point in width that can reach the Apennines by extension from a minimum of 30 km up to a maximum of 250 km where, between Ancona and Monte Argentario.