The Apennine Mountains (also known as Apennines) are a mountain range consisting of parallel smaller chains extending 750 miles (1,200 km) along the length of peninsular Italy.

The Heroes of Olympus

The House of Hades

The earth spirits, Ourae, attack the Argo II from the mountains, which prevents the six aboard the ship to cross the mountains. The crew of the ship had previously tried to cross the mountains for two days but had been unsuccessful. The six aboard the Argo II are then forced to turn away from the mountains in hopes of coming up with a new plan.

Locations (CHB)
Magical Locations: Olympus | Camp Half-Blood | Camp Jupiter | Aeolia | C.C.'s Spa and Resort | Daedalus' Workshop | Lotus Hotel and Casino | Mount Othrys | Ogygia | Pan's Cave | Sea of Monsters | The Labyrinth | Tartarus
Cities, States, and Towns: Alaska | Bar Harbor | Chicago | Detroit | Gila Claw | Jamestown | Long Island | Manhattan | New York City | Quebec | San Francisco | Vancouver | Westport
Other Locations: Apennine Mountains | Aunty Em's Gnome Emporium | Crusty's Water Bed Palace | Empire State Building | Gateway Arch | Grand Canyon | Greece | Hoover Dam | Junkyard of the Gods | Mount Saint Helens | Polyphemus' Island | ROFL | Rome | Triple G Ranch | Waterland | Mount Etna | Mount Diablo | Mount Tamalpais | Pikes Peak